Let's do one more example just so that we make sure we understand intersection and union. So let's say that I have set A. And set A has the numbers 11, 4, 12, and 7 in it. And I have set B. And it has the numbers 13, 4, 12, 10, and 3 in it. So first of all, let's think about what A intersect B is going to be equal to. Well, it's the things that are in both sets.