I drew the picture, now what? Please help!

A juggler is strolling along a moving walkway while tossing a ball vertically upward to a height of 3.60 m. The juggler strolls at a constant velocity of +1.20 m/s with respect to the walkway, which moves at a constant velocity of +0.50 m/s with respect to the ground. An observer on the ground passes the juggler and notices that the path of the ball is a parabola with a maximum width of +1.80 m. What is the velocity of the observer with respect to the ground? (Assume no air resistance and that a
= g = 9.81 m/s

Thanks

Question

I drew the picture, now what? Please help!

A juggler is strolling along a moving walkway while tossing a ball vertically upward to a height of 3.60 m. The juggler strolls at a constant velocity of +1.20 m/s with respect to the walkway, which moves at a constant velocity of +0.50 m/s with respect to the ground. An observer on the ground passes the juggler and notices that the path of the ball is a parabola with a maximum width of +1.80 m. What is the velocity of the observer with respect to the ground? (Assume no air resistance and that a
= g = 9.81 m/s

Thanks