Question: (a) Some license plates in California consist of one of the digits 1-9, followed by three (not necessarily distinct) letters and then three of the digits 0-9 (not necessarily distinct). How many possible license plates can be produced by this method?
(b) Other California license plates consist of one of the digits 1-9 followed by three letters and then three of the digits 0-9. (The same digit or letter can be used more than once.) How many license plates of this type can be made?
(c) What is the maximum number of license plates in California that can be made assuming plates have one of the two types described in (a) and (b)?