Do you know how to move a variable from one side of an equation to the other?

Yes, Lets look at 

2x=x

In order to move the x over to the other side of the equation, we will have to subtract it.

This means our equation will now look like:

x=0

Another example: 

-x=9x

Now that the x is negative, we have to do the opposite of a negative, which is a positive, which means we would have to add an x on both sides.

Our equation will now look like:

0=10x