I need help with all the work if you help you get all the points and brainliest only if it's correct please help me with the work. its 5th grade so easy for older peeps to help me with

Astuntman jumping off a 20-m-high building is modeled by the equation h=20-5t^2, where t is the same in seconds. a high-speed camera is ready to film him between 15m and 10m above the ground. for which interval of time should the camera film him?

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.

What is another way to express 36 +32