Help on this question please. Show your work.

10. ( 10 points ) You throw a rock up into the air from the top of a cliff. The height of the rock as a function of time is given by h(t)= -9.8t2+15t + 10 , t is measured in seconds and h is measured in meters. a. How high above the cliff will the rock be after 2 seconds? b. When will it again be at the level that you threw it? At that moment , what is the velocity of the rock? c. When will the rock hit the water at ground level? d. When will the rock be at its highest point? What is the highest point