Let’s solve each problem one by one. We’ll calculate carefully and check our work.
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Problem 1: What is 10% of 30?
To find 10% of a number, you can divide it by 10.
30 ÷ 10 =
3
✔ Check: 10% means 10 out of 100 → 10/100 × 30 = 0.1 × 30 = 3 ✔️
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Problem 2: In a school of 80 students, 20% are boys. How many are boys?
20% of 80 = 20/100 × 80 = 0.2 × 80
0.2 × 80 = 16
✔ Check: 10% of 80 is 8, so 20% is 8 + 8 = 16 ✔️
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Problem 3: Allan bought a bicycle that cost $20.00 when it was new. If he eventually sold it for 20% of the original cost, how much was it sold for?
20% of $20 = 0.2 × 20 = $4.00
✔ Check: 10% of 20 is 2, so 20% is 4 ✔️
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Problem 4: Brock earned $85.00 for a week's work. If he paid 20% of it in taxes how much did he pay in taxes?
20% of $85 = 0.2 × 85
Calculate:
0.2 × 80 = 16
0.2 × 5 = 1
Total = 16 + 1 =
$17.00
✔ Check: 10% of 85 is 8.5, so 20% is 8.5 × 2 = 17 ✔️
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Problem 5: In a school of 100 students, 11% are boys. How many are boys?
11% of 100 = 11/100 × 100 =
11
✔ Easy — percent of 100 is just the number itself ✔️
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Problem 6: What is 16% of 25?
16% of 25 = 0.16 × 25
Break it down:
0.10 × 25 = 2.5
0.06 × 25 = 1.5
Add them: 2.5 + 1.5 =
4.0
✔ Or: 16 × 25 = 400 → move decimal two places left → 4.00 ✔️
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Problem 7: Kabir earned $100.00 for a week's work. If he paid 10% of it in taxes how much did he pay in taxes?
10% of $100 = 0.10 × 100 =
$10.00
✔ Super easy — 10% of 100 is always 10 ✔️
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Problem 8: Manan bought a bicycle that cost $55.00 when it was new. If he eventually sold it for 20% of the original cost, how much was it sold for?
20% of $55 = 0.2 × 55
0.2 × 50 = 10
0.2 × 5 = 1
Total = 10 + 1 =
$11.00
✔ Check: 10% of 55 is 5.5, so 20% is 5.5 × 2 = 11 ✔️
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Problem 9: Jamar earned $40.00 for a week's work. If he paid 20% of it in taxes how much did he pay in taxes?
20% of $40 = 0.2 × 40 =
$8.00
✔ Check: 10% of 40 is 4, so 20% is 8 ✔️
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Problem 10: What is 20% of 75?
20% of 75 = 0.2 × 75
0.2 × 70 = 14
0.2 × 5 = 1
Total = 14 + 1 =
15
✔ Or: 10% of 75 is 7.5, so 20% is 7.5 × 2 = 15 ✔️
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Final Answer:
1. 3
2. 16
3. $4.00
4. $17.00
5. 11
6. 4
7. $10.00
8. $11.00
9. $8.00
10. 15
Parent Tip: Review the logic above to help your child master the concept of 7th grade percent word problems worksheet.
