Question

given a rectangle that is 21 cm longer than it is wide. Express the perimeter (in cm) of a rectangle in terms of its width w.

Answer 1

L = W + 21

P = 2(L + W)
P = 2(W + 21 + W)
P = 2(2W + 21)
P = 4W + 42

answer
P = 4W + 42 (cm)