Trying to learn this, please label each step if possible, thanks!

(a) Prove the following statement by strong mathematical induction: Any amount of postage of 64 cents or greater can be paid with 5-cent and 17-cents stamps. (b) Give a recursive definition of the following set of ordered pairs of positive integers. S = {(a, b) a E Z+, b E Z+, a + b is odd, and 3 | b}