Let's use the furthest left point on the triangle to figure out the translation.
Blue triangle = (-5,1)
Black triangle = (-3,-1)
To get from -5 to -3 we moved the triangle 2 units to the right, which means that we added 2.
To get from 1 to -1, we moved the triangle 2 units down, which means we subtracted 2.
Rule: {2, -2}
Hope this helps!