0
Length = Width+6
Area = W * L
Area = W * (W+6)
Multiply it out
Area = W^2 + 6W
Area=72
72 = W^2 + 6W
subtract 72 from both sides
0 = W^2 + 6W - 72
12 * 6 = 72
12 - 6 = 6
Factor it
0 = (W-6)(W+12)
W = 6 and W = -12
Width must be 6 cm because Width can't be negative
L = W+6
L = 6 + 6
L = 12 cm
