The length of a rectangle is twice it's width. If the perimeter is 60, find the dimensions of the rectangle

Let x be the length of the width (b) of the rectangle. So, length, l = 2x

Then,

Perimeter = 60 units

=> 2 (l+b) = 60

=> 2x + x = 60/2

=> 3x = 30

=> x = 30/3

=> x = 10

and, 2x = 2*10 = 20

Hence, length = 20 units

width = 10 units