How do I show this without using Schroeder Bernstein theorem. I think the question is asking to prove Schoeder Berstein thm itself! Please include detailed explanation!

(1) If A and B are sets such that there exist injections f from A into B and g from B into A, then |A| = [BI. (2) If A and B are sets such that there exist a surjective function f : A - B and a surjective function g : B - A, then |A| = [BI