Respuesta :

JcAlmighty
The answer is 56 ft

The perimeter of the rectangle with width w and length l is:
P = 2w + 2l

We know:
w = 7 ft
l = 3w = 3 * 7 = 21 ft

P = 2w + 2l
P = 2 * 7 + 2 * 21
P = 14 + 42
P = 56 ft