11. TWO n-digit integers (leading zeros allowed) are considered equivaient if one is a rearrangement of the other. (For example, 1.2033, 2033]., and 01332 are considered equivalent ve-digi: integers.) (a) How many ve-digit integers are not equivalent? (b) If the digits 1, 3, and 7 can appear at most once, how many nonequivalent ve-digit integers are there