You're not even just thinking about numbers. You could even be the color orange is not in set B, so that would be in the absolute complement of B. I don't see a zebra here in set B, so that would be its complement. But we're saying, what are the things that are not in B but are in A? And that would be the numbers 5, 3, and 12. Now, when we visualized this as B subtracted from A, you might be saying, hey, wait, look, look. OK, I could imagine you took the 17 out, you took the 19 out, but what about taking the 6 out? Maybe you've taken a 6 out, or in traditional subtraction, maybe we would end up with a negative number or something.