When a figure is translated down 4 units, each y-coordinate of the vertices is decreased by 4. When it is translated to the right 3 units, each x-coordinate is increased by 3. Therefore, to apply both translations:
- For the x-coordinate: Add 3 units.
- For the y-coordinate: Subtract 4 units.
The correct description of the effect on the coordinates of the vertices is: Add 3 units to each x-value and subtract 4 units from each y-value.