How do I approach these GRE math problems?

I'm looking for an explanation on how to solve the questions. I'm not interested in the answers. 1. If you join all the vertices of a heptagon, how many quadrilaterals will you get? 2. Four students have to be chosen: 2 girls as the captain and vice-captain, and 2 boys as captain and vice-captain of... show more I'm looking for an explanation on how to solve the questions. I'm not interested in the answers.

1. If you join all the vertices of a heptagon, how many quadrilaterals will you get?

2. Four students have to be chosen: 2 girls as the captain and vice-captain, and 2 boys as captain and vice-captain of the school. There are 15 eligible girls and 12 eligible boys. In how many ways can they be chosen if Sunita is sure to be the captain?

3. How many five digit numbers can be formed using the digits 0, 2, 3, 4, and 5, when repetition is allowed such that the number formed is divisible by 2 or 5 or both?

4. If P(2n+1,n-1):P(2n-1,n) = 3.5, find n.
3 answers 3