So I'm just subtracting this from that side but let me subtract this from that side. Well I could subtract this expression from that but this is equivalent so I'm just going to subtract this from that. And so what do I get? Well let's see, I'm going to have one minus P and then if I subtract one P times one minus P from two P times one minus P, well I'm just going to be left with plus one P times one minus P. And then if I subtract this from that, I'm going to be left with one P times one minus P squared. And we're just going to keep going on and on and on. And so let me simplify this a little bit. If I distribute this negative, this could be plus and then this would be P minus one.