A simple propability question

Two learners are due to take an exam, The probability that Andy will pass is 3/5 and the probability that Brenda will fail is 4/7

first i need to calculate the probability that both will fail

then i need the probability that only one will pass

and..

If brenda fails, the probability that she will pass next time is 2/5

a) calculate the probability that brenda fails again

b) calculate the probability brenda passes having taken the exam for the second time.

Any help is much appreciated!