If you use log(x/y) = log(x) - log(y), then at the very least you can isolate all the terms that have x in them. What is the context of your problem and what have you tried so far?
The best way to improve in physics is too solve problems, so that you become familiar with the material. As such, it will probably help if you go through old homework problems and old tests to make sure you can still do those problems. Also be sure to go through new problems so that you are...