Area =108

It is a rectangle so Length time Width equals Area L x W = A

The width is three feet less than the length. (W+3) = L

Substitute (W+3) for L and use the area formula

(W+3) (W)= 108

W^2 +3W=108

W^2 +3W-108=0

To factor this we two numbers that multiply to equal -108 and subtract to equal 3

(-9 x 12) = 108 and -9+12= 3

(W+12)(W-9)=0

Set both factors to equal to 0 and solve.

W+12=0 W=-12 This won't work because the answer can not be negative.

W-9=0 W=9 This one works. The width is 9 the length is 12