From the given graph,
The coordinates of point B are (-3, 7)
The triangle ABC has translated 5 units to the right and 7 units down
That means the x coordinate of B must add by 5 and the y-coordinate must subtract by 7
The rule is (x + 5, y - 7)
The image of point B is B'
B' = (-3 + 5, 7 - 7)
B' = (2, 0)
The image of point B is (2, 0)