Answer :

Okay, you substitute the y in y=9x-9. It gives us, 9=9x-9. you add nine to both sides to eliminate the -9 on the right side of the equation. So far we have, 18=9x. Divide both sides by 9. We get 2=x. And thats your answer.
y = 9x - 9
y = 9

   9 = 9x - 9
+ 9        + 9
18 = 9x
 9      9
  2 = x
y = 9x - 9
y = 9(2) - 9
y = 18 - 9
y = 9
(x, y) = (2, 9)