I need help on how to understand and solve this problem:

A ball is thrown upward at a speed of 48 feet per second from the edge of a cliff 432 feet above ground. Find its height above groundtseconds later.

When does it reach its maximum height?

When does it hit the ground?

(Note: Give the upward direction as positive, physics tells us that the acceleration of the ball is -32 feet per $\displaystyle second^2$.