Congruent squared, with side lengths, X, or cut from the corners of a 9 x 15” piece of cardboard to form an open box. Which equation model, the surface area, a of the open box after the corners are cut away.
a) V=(15+x)(9+x)
b) A=135-4x^2
c) A=135-4x
d) A=(15-x)(9-x)
