Perimeter of a rectangle

A rectangle has a length of 12 and a width of 2x. If the area of the rectangle is 12, what is the rectangle's perimeter?

width = 2x
length = 12
area = 12

Area of a rectangle = length x width

2x(12) = 2x   {area is length x width}
24x = 12   {multiplied}
x = 0.5   {divided each side by 24}
2x = 1 = width   {substituted 0.5, in for x, into 2x}
width = 1 and length = 12 

Perimeter of a rectangle is 2(width) + 2(length)
= 2(1) + 2(12)   {substituted length and width into perimeter formula}
= 2 + 24   {multiplied}
= 26   {added}

Perimeter is 26

{a shortcut would be to identify that the length was the same as the area,
therefore the width would have to be 1}

- Algebra House