A cabin crew of a large airline company consists of 2 pilots and 5 flight attendants. The members of the crew are selected out of 10 pilots and 20 flight attendants.

a. How many different combinations are possible?

b. The brother of one of the pilots is a flight attendant. If the crew is selected at random, what is the probability that both siblings will be selected?

c. What is the probability that neither sibling will be selected?