In how many different ways can a panel of 12 jurors and 2 alternates be chosen from a group of 15 prospective jurors?

JCL Computers has five vacancies in its executive trainee program. How many ways can the company select five trainees from a group of 15 female and 15 male applicants if the vacancies;
(a) can be filled by any conbination of men and women?
(b) must be filled by two men and three women?

What is your attempt?