Question 801383
If P = 2L + 2W where L and W are Length and Width Respectively
then 
40 = 2L + 2W;
since W = (L/2)-1

then 40 = 2L + 2((L/2)-1)
simplified to 40 = 3L - 2

42/3 = L

solve for L you will find that L = 14 
plug that into the equation for W such 
that

W = (14/2)-1 = 6