AlgebraMediumPercent increase followed by a subtraction
Algebra practice question
A number is increased by 20%, and 15 is then subtracted from the result, giving 33. What is the original number?
Answer: 40
1.2n − 15 = 33 → 1.2n = 48 → n = 40.
Common wrong answers
- If you answered 15
- 15 comes from 1.2n = 18, subtracting 15 instead of adding it.
- If you answered 48
- 48 is 1.2n, the number after the increase.
- If you answered 57.6
- 57.6 comes from multiplying 48 by 1.2 instead of dividing.
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