Problem Solving — Screws and Nails

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Problem Solving — Screws and Nails

Problem Solving GMAT Question of the Day
Explanation
Let S be the number of screws, N the number of nails, and H the number of hooks that Joseph bought.

Simplifying by using cents instead of dollars, we have:
(a) 1N + 2H + 3S = 32

We also know the following:
(b) N + H + S = 18
(c) N = 2S

Substituting (c) into both (a) and (b) gives us:
(a) 5S + 2H = 32
(b) 3S + H = 18

To solve the above equations, we can multiply (b) by 2 and subtract (a):
6S + 2H - 5S - 2H = 36 - 32
Thus, S = 4, N = 8, and H = 6.

The correct choice is B.