Answer:
Let the length parallel to the house be y
let each of the other two equal sides be x
2x + y = 120
y = 120 - 2x
Area = xy
= x(120 - 2x) or -2x^2 + 120x
b) you want the vertex.
x of the vertex is -120/(-4) = 30
when x = 30
y = 60
Maximum area = xy = 1800 ft^2