Wo stones are thrown up simultaneously from the edge of a cliff 200 m

Two stones are thrown up simultaneously from the edge of a cliff 200 m high with initial speeds of 15 m/sand 30 m/s. Verify that the graph shown in figure, correctly represents the time variation of the relative position of the second stone with respect to the first. ’
Neglect the air resistance and assume that the stones do not rebound after hitting the ground. Take g = 10 ms-2. Give the equations for the linear and curved part of the plot.