In order to find your starting point just retrace your steps, when you move left on a graph think of subtracting when you move right think of adding. In this case though we need to do the opposite to find the starting point, -5+9 = 4. (4,0) is the point that you were on after the transition right three times. Now subtract three from four. 4-3=1, your starting point was (1,0).