license plate numbers can be made using 2 letters followed by 4 digits selected from the digits 0 through 9, if a) Letters and digits may be repeated?…

How many different license plate numbers can be made using 2 letters followed by 4 digits selected from the digits 0 through 9, ifa) Letters and digits may be repeated?b) Letters may be repeated, but digits may not be repeated?c) Neither letters nor digits may be repeated?Show reasoning