Can anyone me with the answers from this page

Let f(x) = 3 − x . find the average rate of change of f(x) from x = a to x = a + h and simplify your answer so that no single factor of h is left in the denominator.

Is the power produced directly proportional to the wind speed, give reasons for your answer?

Wich statement could be used to explain why the function h(x)= x^3 has an inverse relation that is also a function