The length of a rectangle is twice it's width. If it's perimeter is 54cm, find its length. Explain!

Let width be w

so length = 2w

perimeter of a rectngle = 2( length + width)

=> 54 = 2( 2w + w)

=> 54 = 2(3w) = 6W

=> w = 54/6 = 9 cm

width = 9 cm

length = 18 cm

:)