Question 143591
Perimeter is the sum of all the sides.

Let w be the width.
L = 2w-4

P = w + l + w + l
28 = w + 2w -4 + w + 2w -4
28 = 6w - 8
36 = 6w
6 = w

l = 12 - 4 
l = 8

Does that work?
28 = 12 + 16 check!