A developer decides to build a fence around a neighborhood park, which is positioned on a

rectangular lot. Rather than fencing along the lot line, he fences x feet from each of the lot's

boundaries. By fencing a rectangular space 141yd² smaller than the lot, the developer saves $432 in

fencing materials, which cost $12 per linear foot. How much does he spend ?

a. $160

b. $456

c. $3,168

d. The answer cannot be determined from the given information.