How do i do this? my teacher makes these problems very

What is the value of r of the geometric series?

Which of the following answers is 5/25 simplified? 1/5 5/5 2/5 1/25

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.