Length and Width of a Rectangle

Question

The length of a rectangle is three times its width. If the perimeter of the rectangle is 112 inches, find its length and width.

Answer 1

Let L be the length of the rectangle and let W be the width. The perimeter is L + W + L + W and the perimeter is 112 so that means we can write 2L + 2W = 112.

Since the width is "W", then three times the width is "3W" and since the length is three times the width then L = 3W. Now we can substitute into the perimeter equation "3W" wherever we see "L".

So instead of 2L + 2W = 112. we can write 2(3W) + 2W = 112 and solve:

6W + 2W = 112

8W = 112

W = 14

Since L = 3W, then L = 3(14) or L = 42

So the length is 42 inches and the width is 14 inches.