The yard behind the Cindy's house is rectangular in shape and has a perimeter of 72 feet. If the length l of the yard is 18 feet longer than the width w of the yard, what is the area of the yard, in square feet?

Let the width of the yard be w.

Since the length is 18feet longer, l = w + 18

Perimeter for rectangle = 2 (l + w)

2 (l + w) = 72

2 (w+18 + w) = 72 Divide 2 on both sides

(w + 18 + w) = 36

2w + 18 = 36

2w = 36 - 18

2w = 18 Divide 2 on both sides

w = 18/2

w = 9

Recall, length l = w + 18, l = 9 + 18 = 27

Hence width, w = 9, length, l = 27

Area of rectangle = l * w = 27 * 9 = 243

Area of rectangular yard = 243 square feet.