Easiest way is to just look at the diagram, plot the last point, and count.
So for example, draw the diagram, and you can see (1,5) and (4,2) are a pair of points which differ by 3 and 3.
Then you have (2,-3), so the last point has to be 3 up and 3 to the left, which is (-1, 0).
You'll...