1. The problem statement, all variables and given/known data I have a very simple question I am having problems with. 2. Relevant equations n= C/V 3. The attempt at a solution Hey guys, This is a very simple equation indeed. I am a mature student and starting up in physics. My mathematics is terrible. So please don't laugh. I can seem to integrate and differentiate but for some reason, I have forgotten something really really really stupid. I rearranged the above formula earlier and to solve for v and I came up with Cn=V. I dont know why I am doing that and this, I had no problem before. So my question is, when changing sides of an equation, how do I know which to move from one side to the other and in what order. Do i start with numerator or denominator. And if so, what order. I have exams coming up and im in a divorce currently and really really simple stuff has completely slipped from my brain. For obvious reasons, I cant ask this question at my university. I am in a bit of a panic.