5) Counting Password - Each character in a password is either a digit [0-9] or lowercase letter [a-z]. How many valid passwords are there with the given restriction(s)?

a) Length 14

b) Length 11 or 12

c) Length 13 and cannot start with a digit

d) Length 16 and cannot start nor end with a digit

e) Length 19 or 17, and must start with a digit