this is my last question and i've been waiting 40 minutes

the graph below shows the height of a kicked soccer ball f(x), in feet, depending on the distance from the kicker x, in feet:

graph of quadratic function f(x) having x intercepts at ordered pairs (0, 0) and (16, 0). the vertex is at (8, 10).

part a: what do the x-intercepts and maximum value of the graph represent? what are the intervals where the function is increasing and decreasing, and what do they represent about the distance and height?

part b: what is an approximate average rate of change of the graph from x = 8 to x = 13, and what does this rate represent?