Algebra practice question

Answer: 45

Let the number be x: x − 0.4x = 0.6x = 27, so x = 27/0.6 = 45. Check: 40% of 45 is 18, and 45 − 18 = 27.

Common wrong answers

If you answered 67.5

67.5 is 27/0.4, treating the 27 as 40% of the number. It is the remaining 60%.

If you answered 37.8

37.8 is 27 × 1.4, adding 40% to 27. The 40% was taken of the original number, not of 27.

If you answered 16.2

16.2 is 27 × 0.6, applying the 60% to 27 instead of solving 0.6x = 27.

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