4 feet 6 inches Step-by-step explanation: P=2(l+w) [the addition of all sides of the rectangle] P = 40' L = 15’6” So, 40' = 2 (15’6’ + w) 40' = 31’ + 2w 9' = 2w 4’6” = w If it's easier you can break it change feet into inches and then change back to feet.