Divide both sides by c2.

Remember, that with an equation you have to do the same on both sides of the equation. In your case you are trying to isolate C2 (which I imagine is the variable name) in c1v1= c2v2. So can you think of something that would take away v2 on the right side so you just get c2 on that side? Hint - divide something on both sides and you will be left with c2 on the right side.

I hope I'm understanding your problem and it's helpful.