Too keep in mind- you can add, subtract, multiply or divide anything however as long as you do it on BOTH SIDES of the equal sign.
To cancel a variable on one side of the equation, preform the opposite operation with it on both sides of the equation.
For example-
2x+5=10
-5 -5
——————
2x=5
— —
2 2
X= 2.5
As you can see I subtracted 5 inside of adding (the opposite) and I did it on both sides. Therefore the 5 gets canceled. Same with the division