(15 pts) the function f(x) = –x^2 + 20x – 75 models the profit from one customer, in dollars, a shop makes for printing photos, where x is the number of photos printed, and f(x) is the amount of profit.
part a: determine the vertex. what does this calculation mean in the context of the problem?

part b: determine the x-intercepts. what do these values mean in the context of the problem?