6.
While transformation with the reflection across the x-axis, the absicssa (x-coordinate) remains the same but ordinate (y-coordinate) changes its sign.
The coordinate of point A is (3,0), coordinate of point B is (1,4) and the coordinate of point C is (5,3).
After transformation the, coordinate with the image can be shown as,
Thus, the coordinates of the image after transformation is A'(3,0), B'(1,-4) and C'(5,-3).