AlgebraHardDifference of two fractions of a number
Algebra practice question
Two thirds of a number exceeds three fifths of the same number by 3. What is the number?
Answer: 45
(2/3)n − (3/5)n = 3 → (10/15 − 9/15)n = (1/15)n = 3 → n = 45.
Common wrong answers
- If you answered 3
- 3 is the difference, not the number.
- If you answered 15
- 15 is the common denominator, not the number.
- If you answered 45/19
- 45/19 comes from (2/3 + 3/5)n = 3, adding instead of subtracting.
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