Problem 1. [15 points (a) Give a regular expression whose language is strings over {a, b} in which the number of as is divisible by 3 (b) Give a regular expression whose language is strings over fa, b, c in which the total number of b's and c's sums to 3. (c) Give a regular expression whose language is strings over {a, b} in which every a is either immediately preceeded or immediately followed by b