Give clear step and explanation.
1. How many five-digit numbers can be formed using all the digits 0, 1, 2, 3, and 4 if
a) the numbers can be divided by 2?
b) the number ends with 0?
2. A parent-teacher committee of a school is formed with 8 members chosen from 5 teachers, 6 parents and the principal. Find the number of ways to form this committee if
a) the principal and 3 teachers must be part of the committee.
b) the committee must have at most 3 teachers and the principal.