3 is the least common multiple for 6 and 21
P = 2(L + W)
P = 60
L = 2W - 3
60 = 2(2W - 3 + W)
60 = 2(3W - 3)
60 = 6W - 6
60 + 6 = 6W
66 = 6W
66/6 = W
11 = W <=== the width is 11 ft
L = 2W - 3
L = 2(11) - 3
L = 22 - 3
L = 19 <=== the length is 19 ft




Answer: B) (2; -2), (4; -1)
Commutative Property is used here