P = perimeter
L = length
W = width
Formula for the perimeter of a rectangle = L + L + W + W or P = 2L + 2W
You know:
P = 110ft
L = W + 5 [length is 5ft greater than the width]
So plug this into the formula:
P = 2L + 2W Substitute/plug in (W + 5) for L
110 = 2(W + 5) + 2W Distribute/multiply 2 into (W + 5)
110 = (2)W + (2)5 + 2W
110 = 2W + 10 + 2W Combine like terms (2W + 2W)
110 = 4W + 10 Subtract 10 on both sides
110 - 10 = 4W + 10 - 10
100 = 4W Divide 4 on both sides to get "W" by itself
25 = W Now that you know the width, plug it into the equation for length
L = W + 5 Plug in 25 for W
L = 25 + 5
L = 30
L = 30 ft
W = 25 ft
PROOF
P = 2L + 2W
110 = 2(30) + 2(25)
110 = 60 + 50
110 = 110