Rewrite the second equation:
This is to make the calculation easier. There are other ways to do this as well.
3y = 3x - 6
Substitute that into the first equation:
Since they are the same thing (=), it is possible to replace 3y.
2x + (3x - 6) = 9
Solve the equation:
2x + 3x = 9 + 6
5x = 15
x = 3
Substitute x = 3 into the first equation:
2(3) + 3y = 9
6 + 3y = 9
3y = 3
y = 1
Answer: x = 3, y = 1