How do you do 4x - 9 = 6x - 13? what do you subtract from both sides?

Simple ...

you have: 4x-9=6x-13

-->>Isolate the variable ... (x)

4x-9=6x-13

-4x - 4x

-9=2x-13

+13 + 13

4=2x

2=x

Plug it in ... to make sure it is correct ...

4 (2) - 9=6 (2) - 13

8-9=12-13

-1=-1

Correct.

Thus, your answer.

To start, you need to subtract 4x from both sides, that way, x is one one sid of the equation.