Yes, you are misunderstanding the first question. Let be the height of the ball relative to the ground, and the height of the floor of the elevator relative to the ground. The height of the ball relative to the floor of the elevator is , and you want to find the maximum value of h (which will occur at a time earlier than the maximum of occurs). You should have that and that , so . To find the maximum, we find , set it equal to zero and solve for time, so that h is maximum at seconds, and you plug that into h(t) to get the maximum value of h.