Set up an equation.
width = x
length = 56 - 2x
Multiplying length * width makes area. 56x - 2x^2 = Area.
y = -2x^2 + 56x
Ax^2 + Bx = C
Solve for the vertex: x = -(b/2a)
-(56/-4) = 14
width = 14 ft.
length = 56 - 2(14) = 28ft.
14*28 = 392 sq. ft.
Graph using y=mx+b. The point of intersection is (3,8)
Y intercept is (0,-4) and the x intercepts are (-2,0) and (2,0)