Algebra practice question

Answer: 11.5 or 23/2

Let p and d be the prices. 3p + 2d = 11 and 5p + 4d = 20. Doubling the first gives 6p + 4d = 22; subtracting gives p = 2, then d = 2.5. So 2(2) + 3(2.5) = 11.5.

Common wrong answers

If you answered 9

9 uses d = 1.5, a slip in solving for d.

If you answered 11

11 copies the first total; the combination asked for is different.

If you answered 10.5

10.5 comes from swapping the two prices.

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