Probability question

I'm completely stuck on this question and I'm pretty sure my answers are wrong. Any help would be much appreciated!!

Undergraduate economists can either do a single Honours degree
or a joint Honours degree. Their society has a party which they all
attend. They are joined by other joint Honours students who are not
doing any economics at all. 55% of people are doing a joint Honours
degree and 65% of people are doing some economics. 100 people
attend the party.

a) What is the probability that a single Honours student at the party is
also doing economics?

b) What is the probability that an economist is a single Honours
student?

c) What is the probability that a joint Honours student is studying
economics?

d) What are the odds that a student is a joint Honours economist?

e) Five joint honours students leave the room. What is the probability
that they are a mixed group of economists and non-economists?