How do we solve this?

Let X : {0,1,2,...,n 1,,n} and Y : {n,n+ 1,...,2,1,0},Where n is a positive integer. Dene f I P2(X) X 792(Y) > 793(X UY) U P4(X U Y) by f(A, B) = A o B. Suppose that f (A, B) : f (C, D). This applies to all of the following parts. Helpful fact: X F] Y : {0} (the singleton). (a) Suppose that 0 E A. Prove that A : C. Hint: What form does the set A take? (b) Suppose that 0 A. Prove that A : C'. (C) Prove that f is injective