You are correct in your thinking about the first problem:

and

for any

So it does cancel out.

For the second problem, you have

The first step here is to get all the terms over to one side, and all the other terms over to the other side thus:

The next step is to add the fractions on each side. Repeat after me:adding fractions is a matter of getting a common denominator.That's your mantra. Can you continue from here?