For a menu that is being created you can place 15 options within it. There are 13 meat offerings and 8 non-meat offerings to choose from?

(a) In how many ways can 15 entrees be randomly selected out of the 21 meat and non-meat offerings? Show work?

(b) In how many ways can 15 entrees be chosen, if 9 must be meat and 6 must be non-meat? Show work?

(c) If 15 entrees are randomly selected from the 21 offerings, what is the probability that 9 are meat and 6 are non-meat?

Round answer to nearest ten-thousandth

For this problem, I just don't know where to start. any help would be amazing.