Answer :
P = 2(L + W)
P = 112
L = 35
112 = 2(35 + W)
112 = 70 + 2W
112 - 70 = 2W
42 = 2W
42/2 = W
21 = W <=== width is 21 inches
P = 112
L = 35
112 = 2(35 + W)
112 = 70 + 2W
112 - 70 = 2W
42 = 2W
42/2 = W
21 = W <=== width is 21 inches