And that's especially valuable, because as we'll see, not every scenario is going to fit so cleanly into what we did. There might be some tweaks on this, where maybe only person B likes sitting in one of the chairs, or who knows what it might be, and then your formula is going to be useless. So I like reasoning through it like this, but I just showed you this so that you could connect it to a formula that you might see in a lecture, or in a class.