Final answer:
The light will be located at the midpoint of the longest side in the transformed flower bed, but mirrored below the x-axis.
Step-by-step explanation:
The transformation (x, y) → (x, -y) reflects the flower bed across the x-axis. The new flower bed will have the same shape and size as the original, but will be a mirror image of it below the x-axis.
Since the light was originally placed at the midpoint of the longest side, which is the same as the x-axis, the light will now be located at the midpoint of the longest side in the transformed flower bed, but mirrored below the x-axis.