Concise Mathematics Selina Solutions Class 10 ICSE Chapter 1 GST [Goods and Services Tax]
ICSE Class 10 Maths GST questions test how well you apply percentage, discount, CGST, SGST, IGST and Input Tax Credit in bill-based sums. In Selina Concise Mathematics Class 10 Chapter 1, the safe method is to first find the taxable value, then decide whether the transaction is intra-state or inter-state, and only then add the correct GST component.
This replacement page is written as a teacher’s working note for students revising Chapter 1 GST. It gives the formula method first, then step-by-step solutions for the GST sums listed on the page, followed by original worked examples, common mistakes and a quick answer index.
For broader revision, use this page with ICSE Class 10 solutions, ICSE Class 10 Maths study material and chapter-wise ICSE solutions.
GST formulas for ICSE Class 10 Maths
Before solving any bill question, write the transaction type. This single step prevents most GST mistakes.
| Situation | Formula or rule | How to use it |
|---|---|---|
| Discount | \text{Discount}=\dfrac{\text{Discount rate}}{100}\times \text{Marked Price} | Subtract it from the marked price before adding GST. |
| Taxable value | \text{Taxable value}=\text{Marked Price}-\text{Discount} | GST is calculated on this value. |
| Intra-state supply | \text{CGST}=\text{SGST}=\dfrac{\text{GST rate}}{2} | Use when seller and buyer are in the same state. |
| Inter-state supply | \text{IGST}=\text{GST rate} | Use when seller and buyer are in different states. |
| Amount of bill | \text{Bill amount}=\text{Taxable value}+\text{GST} | Add CGST and SGST, or add IGST. |
| Input Tax Credit | \text{GST payable}=\text{Output GST}-\text{Input GST} | Used when a dealer buys and sells taxable goods or services. |
Concept snapshot: CGST, SGST and IGST
Think of GST as one tax amount that changes its label depending on the route of the sale. If the sale stays within one state, the tax is split equally into two boxes: CGST and SGST. If the sale crosses state borders, the full GST goes into one box: IGST. The bill total may remain the same; only the tax headings change.
Exercise 1(A) solved questions: GST [Goods and Services Tax]
Question 1(a): Marked price ₹\,1500, discount 20\%, GST 18\%
Step 1: Find the discount on the marked price.
\text{Discount}=\frac{20}{100}\times 1500=300
Step 2: Find the taxable value after discount.
\text{Taxable value}=1500-300=1200
Step 3: Add GST at 18\%.
\text{GST}=\frac{18}{100}\times 1200=216
\text{Amount paid}=1200+216=1416
Final answer: ₹\,1416. The correct option is ₹\,1416.
Question 1(b): Articles A and B with different GST rates
Step 1: For article A, calculate GST on ₹\,1000 at 5\%.
\text{GST on A}=\frac{5}{100}\times 1000=50
\text{Amount for A}=1000+50=1050
Step 2: For article B, calculate GST on ₹\,2000 at 12\%.
\text{GST on B}=\frac{12}{100}\times 2000=240
\text{Amount for B}=2000+240=2240
Step 3: Add both article amounts.
\text{Total amount}=1050+2240=3290
Final answer: ₹\,3290. The correct option is ₹\,3290.
Question 1(c): GST reduced from 12\% to 5\%, price falls by ₹\,14
Step 1: Let the original price of the article before GST be ₹\,x.
Step 2: The fall in GST rate is 12\%-5\%=7\%.
\frac{7}{100}\times x=14
Step 3: Solve for x.
x=\frac{14\times 100}{7}=200
Final answer: The original price of the article is ₹\,200. The correct option is ₹\,200.
Question 1(d): Rajasthan to Punjab at GST 28\%
Step 1: Rajasthan and Punjab are different states, so this is an inter-state supply.
Step 2: In an inter-state supply, GST is charged as IGST. CGST and SGST are not charged separately.
Final answer: \text{SGST}=0\%. The correct option is 0\%.
Question 1(e): Inter-state sale when GST rate is 18\%
Step 1: In an inter-state sale, the full GST rate is charged as IGST.
Step 2: Therefore, if the GST rate is 18\%, then IGST is also 18\%.
Final answer: \text{IGST}=18\%. The correct option is \text{IGST}=18\%.
Question 1(f): Marked price ₹\,1375, CGST 4\%
Step 1: Since CGST is 4\%, SGST is also 4\% for an intra-state transaction.
\text{Total GST rate}=4\%+4\%=8\%
Step 2: Calculate total GST.
\text{GST}=\frac{8}{100}\times 1375=110
Step 3: Add GST to the marked price.
\text{Price including GST}=1375+110=1485
Final answer: ₹\,1485. The correct option is ₹\,1485.
Question 1(g): Marked price ₹\,2000, discount ₹\,500, GST 12\%
Step 1: Subtract the discount from the marked price.
\text{Taxable value}=2000-500=1500
Step 2: Calculate GST at 12\%.
\text{GST}=\frac{12}{100}\times 1500=180
Step 3: Add GST to the taxable value.
\text{Amount paid}=1500+180=1680
Final answer: ₹\,1680. The correct option is ₹\,1680.
Question 2: Transaction within Delhi
Step 1: Find the discount on ₹\,12000.
\text{Discount}=\frac{30}{100}\times 12000=3600
Step 2: Find the discounted value.
\text{Discounted value}=12000-3600=8400
Step 3: The transaction is within Delhi, so GST 18\% is split equally.
\text{CGST}=9\%\text{ of }8400=\frac{9}{100}\times 8400=756
\text{SGST}=9\%\text{ of }8400=\frac{9}{100}\times 8400=756
Step 4: Since the transaction is intra-state, \text{IGST}=0.
\text{Amount of bill}=8400+756+756=9912
Final answer: Discount =₹\,3600, discounted value =₹\,8400, CGST =₹\,756, SGST =₹\,756, IGST =₹\,0, amount of bill =₹\,9912.
Question 3: Transaction from Delhi to Jaipur
Step 1: Find the discount on ₹\,50000.
\text{Discount}=\frac{20}{100}\times 50000=10000
Step 2: Find the discounted value.
\text{Discounted value}=50000-10000=40000
Step 3: Delhi to Jaipur is an inter-state transaction. Therefore, CGST and SGST are 0, and IGST is 28\%.
\text{IGST}=\frac{28}{100}\times 40000=11200
\text{Amount of bill}=40000+11200=51200
Final answer: Discount =₹\,10000, discounted value =₹\,40000, CGST =₹\,0, SGST =₹\,0, IGST =₹\,11200, amount of bill =₹\,51200.
Question 4: Intra-state bill for four goods or services
Step 1: For each item, find the discounted value and then add CGST and SGST.
| MRP | Discount | Discounted value | CGST | SGST | Total |
|---|---|---|---|---|---|
| ₹\,12000 | 30\% | \frac{70}{100}\times 12000=8400 | \frac{6}{100}\times 8400=504 | 504 | 9408 |
| ₹\,15000 | 20\% | \frac{80}{100}\times 15000=12000 | \frac{9}{100}\times 12000=1080 | 1080 | 14160 |
| ₹\,9500 | 30\% | \frac{70}{100}\times 9500=6650 | \frac{14}{100}\times 6650=931 | 931 | 8512 |
| ₹\,18000 | 40\% | \frac{60}{100}\times 18000=10800 | \frac{2.5}{100}\times 10800=270 | 270 | 11340 |
Step 2: Add the four totals.
\text{Total bill}=9408+14160+8512+11340=43420
Final answer: The amount of the intra-state bill is ₹\,43420.
Question 5: Inter-state bill using the same data as Question 4
Step 1: In inter-state transactions, the total GST is charged as IGST. Since Question 4 gives CGST rates, double them to get the IGST rate.
| MRP | Discounted value | IGST rate | IGST | Total |
|---|---|---|---|---|
| ₹\,12000 | 8400 | 12\% | \frac{12}{100}\times 8400=1008 | 9408 |
| ₹\,15000 | 12000 | 18\% | \frac{18}{100}\times 12000=2160 | 14160 |
| ₹\,9500 | 6650 | 28\% | \frac{28}{100}\times 6650=1862 | 8512 |
| ₹\,18000 | 10800 | 5\% | \frac{5}{100}\times 10800=540 | 11340 |
Step 2: Add the totals.
\text{Total bill}=9408+14160+8512+11340=43420
Final answer: The amount of the inter-state bill is ₹\,43420.
Question 6: Mumbai dealer supplies goods to Delhi dealer
Step 1: Mumbai to Delhi is inter-state, so IGST is charged. Since SGST is 9\%, total GST is 18\%.
| Rate | Quantity | Value before discount | Discounted value | IGST | Total |
|---|---|---|---|---|---|
| ₹\,180 | 10 | 180\times 10=1800 | 1800 | \frac{18}{100}\times 1800=324 | 2124 |
| ₹\,260 | 20 | 260\times 20=5200 | \frac{80}{100}\times 5200=4160 | \frac{18}{100}\times 4160=748.80 | 4908.80 |
| ₹\,310 | 30 | 310\times 30=9300 | 9300 | \frac{18}{100}\times 9300=1674 | 10974 |
| ₹\,175 | 20 | 175\times 20=3500 | \frac{70}{100}\times 3500=2450 | \frac{18}{100}\times 2450=441 | 2891 |
Step 2: Add the row totals.
\text{Total bill}=2124+4908.80+10974+2891=20897.80
Final answer: The total amount of the bill is ₹\,20897.80.
Question 7: Services from Delhi to Agra
Step 1: Delhi to Agra is inter-state, so apply the given GST rate as IGST.
| Number of services | Cost per service | Service value | IGST | Total |
|---|---|---|---|---|
| 8 | ₹\,680 | 8\times 680=5440 | \frac{5}{100}\times 5440=272 | 5712 |
| 12 | ₹\,320 | 12\times 320=3840 | \frac{12}{100}\times 3840=460.80 | 4300.80 |
| 10 | ₹\,260 | 10\times 260=2600 | \frac{18}{100}\times 2600=468 | 3068 |
| 16 | ₹\,420 | 16\times 420=6720 | \frac{12}{100}\times 6720=806.40 | 7526.40 |
Step 2: Add all totals.
\text{Bill amount}=5712+4300.80+3068+7526.40=20607.20
Final answer: The amount of the bill is ₹\,20607.20.
Question 8: Discount allowed when 80 or more articles are purchased
Step 1: Article A has quantity 120, so 20\% discount is allowed.
\text{Value of A before discount}=180\times 120=21600
\text{Discounted value of A}=\frac{80}{100}\times 21600=17280
\text{GST on A}=\frac{5}{100}\times 17280=864
\text{Total for A}=17280+864=18144
Step 2: Article B has quantity 50, so no discount is allowed.
\text{Value of B}=120\times 50=6000
\text{GST on B}=\frac{12}{100}\times 6000=720
\text{Total for B}=6000+720=6720
Step 3: Add both article totals.
\text{Total amount}=18144+6720=24864
Final answer: The total amount is ₹\,24864.
Question 9: Telecom service cost ₹\,750, GST 18\%
Step 1: Calculate GST on the service cost.
\text{GST}=\frac{18}{100}\times 750=135
Step 2: Add GST to the cost of service.
\text{Amount of bill}=750+135=885
Final answer: The amount of the bill is ₹\,885.
Question 10: Health insurance premium when SGST is ₹\,900
Step 1: GST rate is 18\%, so SGST is 9\%.
Step 2: Let the premium before GST be ₹\,x. Given SGST is ₹\,900.
\frac{9}{100}\times x=900
x=\frac{900\times 100}{9}=10000
Step 3: Since CGST equals SGST, CGST is also ₹\,900.
\text{Total premium including GST}=10000+900+900=11800
Final answer: The total annual premium including GST is ₹\,11800.
Question 11: Hotel room and extra bed for two days, GST 28\%
Step 1: Find the daily taxable value.
\text{Daily charge}=5000+1000=6000
Step 2: Find the taxable value for two days.
\text{Taxable value for two days}=6000\times 2=12000
Step 3: Calculate GST at 28\%.
\text{GST}=\frac{28}{100}\times 12000=3360
Final answer: The GST charged by the hotel is ₹\,3360. If the full bill amount is required, it is ₹\,12000+₹\,3360=₹\,15360.
Additional worked examples for GST and ITC
These examples are not copied from the exercise. They are included to strengthen the methods that students commonly need in Selina GST questions.
Worked Example 1: Find the price before GST from the final bill
A shopkeeper charges 18\% GST and the final bill is ₹\,5900. Find the taxable value before GST.
Step 1: If taxable value is ₹\,x, then amount including 18\% GST is 118\% of x.
\frac{118}{100}\times x=5900
Step 2: Solve for x.
x=\frac{5900\times 100}{118}=5000
Final answer: The taxable value before GST is ₹\,5000.
Worked Example 2: Same taxable value, intra-state and inter-state bills
The taxable value of goods is ₹\,8000 and GST is 12\%. Compare the tax split for an intra-state and an inter-state bill.
Step 1: Find the total GST.
\text{GST}=\frac{12}{100}\times 8000=960
Step 2: For intra-state supply, split GST equally.
\text{CGST}=480,\quad \text{SGST}=480
Step 3: For inter-state supply, charge the full amount as IGST.
\text{IGST}=960
\text{Final bill}=8000+960=8960
Final answer: The bill amount is ₹\,8960 in both cases; only the tax headings change.
Worked Example 3: Input Tax Credit for a dealer
A dealer buys goods worth ₹\,50000 and sells them for ₹\,70000. GST is 18\% in both cases. Find the GST payable after Input Tax Credit.
Step 1: Calculate input GST on purchase.
\text{Input GST}=\frac{18}{100}\times 50000=9000
Step 2: Calculate output GST on sale.
\text{Output GST}=\frac{18}{100}\times 70000=12600
Step 3: Subtract input GST from output GST.
\text{GST payable}=12600-9000=3600
Final answer: The GST payable after Input Tax Credit is ₹\,3600.
Examiner’s mindset for ICSE GST sums
In a GST solution, the final answer is not enough. A student should show the taxable value after discount, identify the transaction type, write the correct tax component and then calculate the bill amount. Marks are commonly lost when students calculate GST on the marked price even after a discount is given, or when they split IGST into CGST and SGST in an inter-state question.
In table-based questions, keep one row per item and write a total at the end. This makes arithmetic errors easier to spot during revision.
Common mistakes students make in GST questions
- Calculating GST before discount: Correct method is \text{GST} on \text{Marked Price}-\text{Discount}, unless the question states otherwise.
- Using SGST in inter-state supply: For different states, use IGST. CGST and SGST are 0 in the school-level bill format.
- Forgetting that CGST rate is half of total GST: If total GST is 18\%, then CGST is 9\% and SGST is 9\% in an intra-state bill.
- Treating CGST as total GST: If a question says CGST is 4\%, then total GST is 8\% for an intra-state transaction.
- Dropping paise values: Keep values such as ₹\,748.80 and ₹\,460.80 unless the question asks for rounding.
Quick answer index
| Exercise | Question | Answer |
|---|---|---|
| 1(A) | 1(a) | ₹\,1416 |
| 1(A) | 1(b) | ₹\,3290 |
| 1(A) | 1(c) | ₹\,200 |
| 1(A) | 1(d) | \text{SGST}=0\% |
| 1(A) | 1(e) | \text{IGST}=18\% |
| 1(A) | 1(f) | ₹\,1485 |
| 1(A) | 1(g) | ₹\,1680 |
| 1(A) | 2 | Bill amount =₹\,9912 |
| 1(A) | 3 | Bill amount =₹\,51200 |
| 1(A) | 4 | Intra-state bill =₹\,43420 |
| 1(A) | 5 | Inter-state bill =₹\,43420 |
| 1(A) | 6 | ₹\,20897.80 |
| 1(A) | 7 | ₹\,20607.20 |
| 1(A) | 8 | ₹\,24864 |
| 1(A) | 9 | ₹\,885 |
| 1(A) | 10 | ₹\,11800 |
| 1(A) | 11 | GST charged =₹\,3360 |
Authoritative references for this chapter
This study page follows the standard ICSE Class 10 Mathematics treatment of Commercial Mathematics and GST. For official syllabus and examination context, students should refer to the CISCE official website. For foundational percentage and commercial arithmetic practice, the overlapping school-level concepts may also be checked through NCERT learning resources. The worked GST methods here are aligned to Selina Concise Mathematics Class 10, Chapter 1: GST [Goods and Services Tax].
Frequently Asked Questions
How do I decide whether to use CGST and SGST or IGST in ICSE Class 10 GST sums?
Use CGST and SGST in equal parts when the buyer and seller are in the same state or union territory. Use IGST when the supply is from one state to another state.
Is GST calculated before or after discount in Selina Class 10 GST questions?
GST is calculated on the taxable value after subtracting the discount from the marked price, unless the question clearly says something different.
If CGST is given as 4\%, what is the total GST rate?
For an intra-state transaction, SGST is also 4\%. Therefore, the total GST rate is 8\%.
What is Input Tax Credit in Class 10 GST?
Input Tax Credit is the tax already paid on purchases. In GST sums, tax payable is usually found by subtracting input GST from output GST.
Why do intra-state and inter-state GST bills sometimes have the same final amount?
The final amount can be the same because the total GST rate is the same. In intra-state bills it is split into CGST and SGST, while in inter-state bills it is charged as IGST.