Could you attach an image of the slope? Because i dunno what lesson you're on....
:/
P = 2(L + W)
P = 292
L = 5W - 4
292 = 2(5W - 4 + W)
292 = 2(6W - 4)
292 = 12W - 8
292 + 8 = 12W
300 = 12W
300/12 = W
25 = W <=== width is 25 ft
L = 5W - 4
L = 5(25) - 4
L = 125 - 4
L = 121 <=== length is 121 ft