Questions that I need help correcting.

1) In how many ways can a six member committee form a subcommittee with at least two members?

2) A new theme park will have five roller coasters, six water rides, and eight suspension rides. How many different sets of rides could you try at this park?

3) What are the first three terms of the expansion of (x^2/7 - x/49)^6 ?

4) A project team of up to 5 people is being formed from a staff of 15. How many such teams are possible?