perimeter = length + length + width + width
if the perimeter is 28, then:
28 = length + length + width + width
if you know that the length is 4 more than twice the width, then:
length = 4 + 2 x width
(using L as length, and w as width then: L = 4 + 2w)
if you substitute that back into the equation
28 = L + L + w + w
you should get
28 = 4 + 2w + 4 + 2w + w + w
combine the 4's and the ws
28 = 8 + 6w
subtract both sides by 8
22 = 6w
divide both sides by 6
w = 3 2/3
