Simple Probabilities Plz Help

Hey,

Can someone plz answer the following questions and provide explanation.

1. P(E)=0.25 and 20 outcomes make up event E. Determine the number of outcomes?

2. There are 7 girls, 9 boys in a school camera club. The club needs to form a committee of 6 random people. Determine the outcome if:

a) The committee has no boys.

b) The committee has at least 1 girl.

3. You have a regular 6 side die. You roll it 2 times. Determine if:

a) Probability that you roll a sum of 7.

b) Probability that you roll a sum of 7 if the first roll is 5.

Any help would be greatly appreciated.

Thanx