MR-560 / 560. problem

Simplify the following expression:

3x-3y2x+2y·x2-y2x2-2·x·y+y2

3(x-y)2(x+y)·x-yx+yx-y2=

=3(x-y)2(x+y)·x-yx+yx-y2

=32