1. The lines y = 1, y = 3, and y = x are drawn along with the point P = (3,0). For certain slopes m, the line P through with slope m will intersect the three given lines so that one of the three points of intersection is the midpoint of the other two points. Find all such values of m.
(Please provide an explanation to your solution, and in the problem y = x is the line with slope 1, not y = the variable x)