Probability

Sandra's music bag contains:

3 cds of country music

6 cds of rock and roll

4 cds of rap music

5 cassette tapes of country music

1 cassette tape of rock and roll

3 cassette tapes of rap music

a) As Sandra drives, she often reaches into her bag and randomly pulls out some music. What is the probably that she will select some rap music?

b) Find P(CD), that is, the probability that she will randomly select a CD (of any type of music).

c) Find the probability that she will select a cassete of country music.

d) Find the probability that the music she randomly selects isnotrock and roll.

Please help I don't know how to find probability because Im not sure but I think theres a special way to do it. 'thanks.