The closest point above on this line is (0,9)
You can find this by using the rise over run method. Since the slope is -2, we can move to the next whole number point by observing the fraction 2/-1.
Rise = 2
Run = -1
If you start on the point (1,7) and rise two, it will bring you to (1,9), then you have to move back one space (or run) to (0,9).