## Thinking Mathematically (6th Edition)

We have 4 different people, and we need to select 2 speakers for an event. For convenience, we'll refer to those people as A, B, C, and D. If we select A, we can select either B, C, or D to go as well, which means that there are 3 ways to select the members so that A goes. If we don't select A, and we select B, we can select either C or D to go with as well, which means that there are 2 ways to select the members so that A doesn't go and B goes. If neither A nor B goes, the only combination remaining is for both C and D to go. This gives us a total of $3+2+1=6$ ways to select the speakers.