The length of a rectangular box is 2 units less than its width.

If the area of the box is 15 units square.

Find the perimeter of the box.

Length, l

width, w

l = w - 2

15 = lw

15 = (w-2) w

w^2 - 2w = 15

w^2 - 2w - 15 = 0

w^2 - 5w + 3w - 15 = 0

w (w - 5) + 3 (w - 5) = 0

(w + 3) (w - 5) = 0

w = 5 or w = - 3

possible not possible

width = 5 units

length = 3 units