1. A man has 5 different suits, 7 different shirts and 4 different pairs of shoes. In how many ways can this man wear a suit, a shirt, and a pair of shoes? 2. In a certain country, license plate...

Please answer Number 3 only. Show the given, formula and then the solution together with the final answer

Extracted text: 1. A man has 5 different suits, 7 different shirts and 4 different pairs of shoes. In how many ways can this man wear a suit, a shirt, and a pair of shoes? 2. In a certain country, license plate numbers have 3 letters followed by 3 digits. How many different license plate numbers can be formed? (letters and digits may be repeated). 3. Using the digits 1, 2, 3 and 4, how many 4 digit numbers can be formed if a) The first digit must be 1 and repetition of the digits is allowed? b) The first digit must be 1 and repetition of the digits is not allowed?