AlgebraEasy–MediumTwo lengths from a total and a difference
Algebra practice question
Two planks together measure 10 metres, and one is 2 metres longer than the other. How long, in metres, is the longer plank?
Answer: 6
Let the shorter be s: s + (s + 2) = 10, so 2s = 8, s = 4, and the longer is 6.
Common wrong answers
- If you answered 4
- 4 is the shorter plank.
- If you answered 5
- 5 halves the total, ignoring the difference.
- If you answered 8
- 8 is 10 − 2, forgetting to halve.
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