Please help me to solve these problems

Question

Exercise 1:

A young boy asks his mother to get 5 picture card from his collections of 10 flower picture cards and 5 sports picture cards. How many are there that his mother can get 3 flower and 2 sports picture cards?

Exercise 2 :

A present and a treasurer are to be chosen from a student club consisting of 50 people. How many different choices of officers are possible if (1) there are no restrictions; (2) A will serve only if he is a president; (3) B and C will serve together or not at all; (4) D and E will not serve together?

Answer 1

(10 choose 3)(5 choose 2) = 10*9*8/(3*2) * (5*4/2) = 720/6 * 10 = 120

50 pick 2 = 50*49 = 2450

A is president, then 49 choices

2 for B and C

50 * 48 = 2400