The bearing of the ball from the boy, given the bearing N72E from the ground to the ball, is S72W or N72W from the ball's perspective without considering the 180-degree turn.
The question related to bearings can be resolved by understanding that bearings are measured from the north direction clockwise. If the bearing of the ball from the ground is N72E, this means it is 72 degrees east of the north.
Hence, from the ball's perspective, to look back at the boy, it needs to look towards the North and then turn 180 degrees (which would be directly south) and then adjust an additional 72 degrees to the west.
Therefore, the bearing from the ball to the boy would be S72W (or N72W from the ball's perspective if we do not consider it has rotated 180 degrees and just took the reciprocal).