How to do 18-7x = 2x-9

How to do 18-7x = 2x-9

If you add or subtract the same number on both sides of the equation, the equation is still equal. Has this teacher taught you?
18-7x=2x-9
18-7x + 7x = 2x-9 + 7x (add 7x to both sides of the equation)
18 = 9x-9 (finishing)
18 + 9 = 9x-9 + 9 (add 9 to both sides of the equation)
27 = 9x (finishing)
9X=27
X = 3 (divide both sides of the equation by 9)
See?