If I add four water molecules on this side, I balance out the O. But now I have to balance out the H, because now I have four times two, eight H ions on this side or atoms on this side. That means I balance this guy out by adding eight H plus ions to this side, and I get this following reaction. So I'm done with steps three and four. Now let's go to step five. In step five, you basically want to balance out the entire charge down on this side and this side, and then the entire charge down on this side and this side.