all you have to do is plug in the x and y values for each ordered pair into the left hand side of the equation and see if you get 15 = 15. If you do, the ordered pair is a solution; otherwise it is not a solution. For example, let's try (-2,-3); that is x = -2 and y = -3:
2x - 9y = 15
2(-2) - 9(-3) = 15
-4 - (-27) = 15
-4 + 27 = 15
23 = 15
This is obviously not true, so (-2,-3) is not a solution. Now you try it on each of the ordered pairs given in the problem statement.