A rectangular area of land is going to be fenced in for a playground. One side of the playground is adjacent
to a school building, so that side won't need a fence. The sides perpendicular to the school have a side
length of x ft. If there are 400 feet of fencing available, which one of the following expressions gives the area
of the playground in square feet?
a. A (x)= x (400 - 2x)
b. A (x) = 2x 400
c. A (x) = 2x (2x - 400)
d. A (x) = (400 - x) x