The length of a rectangle is three times the width. The area of the rectangle is 108 sq in. What is the width of the rectangle?

Let the width be w inches, so the length is 3w inches. The area is (3w)(w) = 108, giving 3w² = 108 and w² = 36. Since a width must be positive, w = 6 inches; the correct choice is 6 in.

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