x+9=18+-2x
divide 2x from both sides
which makes it 3x+9=18
subtract 9 from the 18
which is 3x=9
divide 3 from both sides
which gives you x=3
x+9=18+(-2x) add the 2x to the x and you should get 3x+9=18. Then you would subtract the 9 from the 18 and should get 3x=9. Then just divide the 9 by the 3 and get x=3 which is your answer. Hope this helps!
