Final answer:
According to the law of reflection, the reflected light ray travels symmetrically to the incident ray with respect to the normal at the point of incidence. Without additional information, only the direction but not the endpoint of the reflected ray can be specified.
Step-by-step explanation:
The question involves the reflection of a light ray from a horizontal surface with a coordinate system. When light is emitted from a source at (0.0, 10.0) and strikes the point (20.0, 0.0), according to the law of reflection, the angle of incidence is equal to the angle of reflection. Thus, the reflected ray will travel symmetrically with respect to the normal at the point of incidence. This means that if we were to trace the path of the reflected ray, it would be a mirror image of the incident ray, relative to the normal line that passes through the point of incidence. Without additional information about the surroundings or any potential obstacles, we can only specify the direction of the reflected ray but not a specific endpoint. However, if it is assumed there are no further interactions, the ray would continue indefinitely on this path.