Help with Statistics project: probability

A survey was done where a random sample of people 18 and over were asked if they preferred comedies, dramas, or neither.
table:
movie type 18-24 25-34 35 and older
comedy 20 25 10
drama 20 20 30
neither 10 15 15
A person is selected random,
(a) Determine the probability that they prefer comedy given they are age 18-24.
(b) Determine the probability that they are 25-34 given that they prefer drama.
Consider a class of 42 students. The students are placed in a hat and 4 names are randomly drawn without replacement.
(a) If the first person drawn was named the class president, second person was named vice president, third person drawn was named secretary, and fourth person drawn was named treasurer how many different results would be possible?
(b) If the class of 42 students cosisted of 25 women determine the probability that all four students randomly selected were women.
suppose a bag contain 20 marbles and 2 marbles are drawn without replacement:
7 white marbles
5 red marbles
8 green marbles
(a) what is the probability that both marbles are white?
(b) what is the probability that neither marbles is green?