Question

Width of a wall is 4 inches less then the length. The border that surrounds the wall is 2 inches wide and has an area of 240 square inches. What are dimensions

Answer 1

the area of the border is the total area minus the area of the wall. So,
if the width of the wall is w, then since there is border on each side, we need

(w+4)(w+4+4)-w(w+4) = 240
8(w+4) = 240
w=26

The wall is 26x30

Answer 2

let w = width , length = w + 4 ... cross section area = w (w + 4)

width with border = w + (2 * 2) = w + 4

length with border = w + 4 + (2 * 2) = w + 8

area with border = (w + 4) (w + 8)

area of border = [(w + 4) (w + 8)] - [w (w + 4)] = 240

solve for w , then substitute back to find the length