From the graph, we can see that the highest point on the graph is (10,2700) (you can use the "min/max" feature to find this point).
Since the highest point has the y-value 2700, this means that the max revenue is $2700. This max revenue occurs when the price is $10 (since the x-value of the vertex is x=10).
Also, the reason why the graph is parabolic is because the equation is a quadratic.