A person throws a rock into a lake from a bridge. Its height h, in meters, can be modeled by the function h(t)= 60-8t-4.9t², where t is the time in seconds.

a) Find the average rate of change of the rock height during the first 2 seconds. Round your answer to the nearest tenth.

b) Estimate the instantaneous rate of change of the rock height after 2 seconds.

Please do question a) and b). I would really appreciate it!!