EDIT: HAVE SOLVED THIS BY MYSELF.

Hey everyone! I'm having a little problem with the last paragraph question of this. If anyone can help, that would be much appreciated. I drew a venn diagram and got the following answers, which are verified by the answers at the back of the book.

For married couples the probability that the husband has passed his driving test is 7/10 and the probability that the wife has passed her driving test is 1/2. The probability that the husband has passed, given that the wife has passed, is 14/15. Find the probability that, for a randomly chosen married couple, the driving test will have been passed by:

a) both of them > 7/15

b) only one of them > 4/15

c) neither of them > 4/15

If two married couples are chosen at random, find the probability that only one of the husbands and only one of the wives will have passed the driving test.

How do I do this last part? the answer is 119/450. Can someone explain how they get that please?