Question 107475
1) L=120m+W
2) 2L+2W=560m

Simplify equation 2:
   2(L+W)=560m
2) L+W=280m

Substitute equation 1 into equation 2:

   (120m+W)+ W=280m
    2W=280m-120m
*   W=80m

Substitute W:
    L+80m=280m
*   L=200m

check: 2(200m)+ 2(80m)=?560
yes, that checks