The "Pre Image" is the image that we started with, so the pink triangle.
The "Image" is the image that we ended with, so the blue triangle.
To determine how far we went from the pre image to the image, we can focus on one point, let's say point "P".
The pre image coordinates for point "P" are 2, 3.
The image coordinates for point "P'" are -1, 0.
To get from x value 2 to x value -3, we subtracted 3.
To get from y value 3 to y value 0, we subtracted 3.
So, our rule for this translation would be A, (x, y) ----> (x-3, y-3).