Let's solve each problem step by step. The general method for
percentage increase or decrease is:
For Increase:
$$
\text{Final Amount} = \text{Original Amount} + (\text{Original Amount} \times \frac{\text{Percentage}}{100})
$$
Or more simply:
$$
\text{Final Amount} = \text{Original Amount} \times \left(1 + \frac{\text{Percentage}}{100}\right)
$$
For Decrease:
$$
\text{Final Amount} = \text{Original Amount} - (\text{Original Amount} \times \frac{\text{Percentage}}{100})
$$
Or:
$$
\text{Final Amount} = \text{Original Amount} \times \left(1 - \frac{\text{Percentage}}{100}\right)
$$
---
Now, let’s solve each one:
---
1) Increase $1500 by 35%
$$
1500 \times (1 + 0.35) = 1500 \times 1.35 = 2025
$$
✔ Answer: $2025
---
2) Decrease $840 by 15%
$$
840 \times (1 - 0.15) = 840 \times 0.85 = 714
$$
✔ Answer: $714
---
3) Increase 820 yards by 70%
$$
820 \times (1 + 0.70) = 820 \times 1.70 = 1394
$$
✔ Answer: 1394 yards
---
4) Decrease 52 inches by 25%
$$
52 \times (1 - 0.25) = 52 \times 0.75 = 39
$$
✔ Answer: 39 inches
---
5) Increase 72 gallons by 12%
$$
72 \times (1 + 0.12) = 72 \times 1.12 = 80.64
$$
✔ Answer: 80.64 gallons
---
6) Increase 120 miles by 36%
$$
120 \times (1 + 0.36) = 120 \times 1.36 = 163.2
$$
✔ Answer: 163.2 miles
---
7) Decrease 82 ounces by 15%
$$
82 \times (1 - 0.15) = 82 \times 0.85 = 69.7
$$
✔ Answer: 69.7 ounces
---
8) Decrease $7000 by 28%
$$
7000 \times (1 - 0.28) = 7000 \times 0.72 = 5040
$$
✔ Answer: $5040
---
9) Increase 120 cm by 32%
$$
120 \times (1 + 0.32) = 120 \times 1.32 = 158.4
$$
✔ Answer: 158.4 cm
---
10) Decrease 180 lb by 14%
$$
180 \times (1 - 0.14) = 180 \times 0.86 = 154.8
$$
✔ Answer: 154.8 lb
---
11) Increase 130 seconds by 22%
$$
130 \times (1 + 0.22) = 130 \times 1.22 = 158.6
$$
✔ Answer: 158.6 seconds
---
12) Decrease 320 minutes by 65%
$$
320 \times (1 - 0.65) = 320 \times 0.35 = 112
$$
✔ Answer: 112 minutes
---
13) Increase 76 miles by 86%
$$
76 \times (1 + 0.86) = 76 \times 1.86 = 141.36
$$
✔ Answer: 141.36 miles
---
14) Decrease $12,000 by 72%
$$
12000 \times (1 - 0.72) = 12000 \times 0.28 = 3360
$$
✔ Answer: $3,360
---
15) Increase $9,000 by 43%
$$
9000 \times (1 + 0.43) = 9000 \times 1.43 = 12,870
$$
✔ Answer: $12,870
---
✔ Final Answers Summary:
| Problem | Answer |
|--------|--------|
| 1 | $2025 |
| 2 | $714 |
| 3 | 1394 yards |
| 4 | 39 inches |
| 5 | 80.64 gallons |
| 6 | 163.2 miles |
| 7 | 69.7 ounces |
| 8 | $5040 |
| 9 | 158.4 cm |
| 10 | 154.8 lb |
| 11 | 158.6 seconds |
| 12 | 112 minutes |
| 13 | 141.36 miles |
| 14 | $3,360 |
| 15 | $12,870 |
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Let me know if you'd like these written in a formatted worksheet style!
Parent Tip: Review the logic above to help your child master the concept of percent change worksheet.
