Question 785659
let L = w + 11
 P = 2W + 2L
70 = 2W + 2(w + 11)
70 = 2W + 2w + 22
70 - 22 = 4W
48 = 4W
48/4 = W
12 = W

check: 
2(12) + 2(12 + 11)= 70
24 + 46 = 70
70 = 70