Question

Laura bends a piece of wire 72 inches long into the shape of a rectangle that is three times as long as it is wide what are the dimensions of the rectangle?

Answer 1

Write an equation system based on the problem
Let w be the width of the rectangle, and l be the length of the rectangle
72 inches represents the perimeter of the rectangle, the equation will be
∴ 2l + 2w = 72
The length is three times of the width, the equation will be
∴ l = 3w

Solve the equation by substitution method. Substitute in 3w as l.
2l + 2w = 72
2(3w) + 2w = 72
6w + 2w = 72
8w = 72
w = 72/8
w = 9
The width of the rectangle is 9 inches

Find the length by subtitution of 9 as w
l = 3w
l = 3(9)
l = 27
The length of the rectangle is 27 inches

The dimension:
length: 27 inches
width: 9 inches