Question 514085
L = W+12
A = L*W = 540 sq ft
A = (W+12)*W = 540
W^2+12W-540 = 0
(W +30)(W-18) = 0
W = -30 or 18
Negative width is nonsense, so
W = 18
L = 18+12 = 30
Answer: Dimensions are length 30, width 18.
Done.