hey aaronj,

the first step with these questions for me is to do a Venn diagram. In this case, it's a really valuable thing to do, because it shows you what the answer is very quickly.

The next step, depending on the method that the question wants you to use is to show what you already know is the answer- or to put it in a more positive way to check what you found using the Venn diagram.

Aand then you should recognise both sides of the intersection!