I need to prove the following:a) Let A, B be sets contained in a universal set U. Suppose that A ???B. prove that P(A) ??? P(B) (power sets)b) Let A, B be sets contained in a universal set U such that A is a subset of B. Suppose that A is countable and B is uncountable. prove that B - A is uncountable. c) Using the Schroeder-Bernstein Theorem, prove that any two intervals of real numbers are numer