I don't quite understand what you want to do. Could you post and example please?

Are you taking about something like;

Simplify: 3x + 16 = x

?

If so, then you can do whatever you want, so far you do it on both sides of the equation. If you add something, add the same thing to the other side.

Here, I'll subtract x from both sides:

3x + 16 - x = x - x

2x + 16 = 0

Then, subtract 16 from both sides:

2x + 16 - 16 = 0 - 16
2x = -16

Then, divide both sides by 2.

\frac{2x}{2} = \frac{-16}{2}

x = -8