Aray of light is reflected off a mirror such that the reflected ray is perpendicular to the original ray, as shown in the diagram. what is the equation of the reflected ray?

The equation of the reflected ray is y+x = 6. Since based on the equation of the original ray is y-x=4 and the equation of the normal line y=5, the point where the normal line, the original ray and the reflected ray intersect is at point (1,5). By definition, substituting the normal line (y=5) and the point (1,5) to the given equations, y+x=6 satisfies the equality and therefore is the equation of the reflected ray