I need help on math i seriously forgot how to do this math problem. XD

Hello people, i have a math question that i need with, me, i will give the correct one brainiest, and for the other correct people, a and 5 stars.

In the 30-60-90 triangle below side s has a length of and side r has a length

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.