Question

The length of a rectangle is three times its width. If the area of the rectangle is 192 ft^2, find its perimeter

Answer 1

Answer: 64 feet.

Explanation:
Perimeter formula: 2l + 2w
Area formula: l•w
Length = 3w
Area = 192 ft$^{2}$
192 = (3w) • w 
192 = 3$w^{2}$
192 ÷ 3 = 3$w^{2}$ ÷ 3
64 = $w^{2}$ 
$\sqrt{64}$ = $\sqrt{ w^{2} }$
8 = w 

Width = 8
Length = 3(8) = 24 
Perimeter = 2(24) + 2(8) = 64 feet.

Answer 2

Lets x = width
length = 3x

A = length times width
A = x * 3x
192 = 3x^2
192/3 = x^2
64 = x^2
8 = x

so width = 8
length = 3x = 3(8) = 24

P = 2(L + W)
P = 2(24 + 8)
P = 2(32)
P = 64

answer
P = 64 feet