9514 1404 393
Answer:
x = 120 dollars
Explanation:
The two factors of the revenue function, x and (2160 -9x), will be zero when the values of x are 0 or 2160/9 = 240. These x-intercepts of the revenue function are symmetrical about the axis of symmetry, which is a vertical line through the vertex of the graph. That vertical line is x = (0 +240)/2 = 120.
That is, the revenue will be maximized for a price x = 120 dollars.