Problem 6: Induction and Recursion Consider a postal system for which the minimum postage required for any service (e.g. mailing a postcard) is 18 cents. [a] Prove by strong induction that any postage 18 can be formed using only 4-cent and 7-cent stamps. (Hint: consider bases cases for 18 thru 21 .) [b] Write a Java/Python-like pseudocode for a function that determines the number of each denomination of stamp for a postage amount 18. (It need not be concerned with lesser cases as they are never used)