Please help thank you very much

A state's population as a function of time t (in years) is given by

P(t) = 44,178,000 + 78,000t and its health care costs are given by C(t) = 47,863,000 + 430,500t + 178t²

a. Create the function representing the state's per capita health care costs (i.e., the average cost per citizen).

b. Find the average rate of change in the per capita health care cost from year 5 to year 11.