Perform each given.Show your solution if possible.

1.In how many way can a comittee of 5 be selected from 9 people?

2.A chairman,a financial secretary,and a general secretary are going to be selected from 9 people.In how many ways can this be done?

3.C(8,3)=n

4.C(n,1)=15

5.C(9,n)=126​