Question 141568
w=L-3
L=L

L*w=28

L(L-3)=28
L^2-3L=28
L^2-3L-28=0
(L-7)(L+4)=0

leaving L=7 or L=-4
The only answer that makes sense is L=7.

Thus, L=7, w=L-3=7-3=4.