Answer:
The profit function is: 

The maximum value is 406, 300 occurring when x = 640. 
Step-by-step explanation:
The revenue function is: 

And the cost function is: 

Then the total profit function will be: 

This is a quadratic function. 
Therefore, the maximum value of the total profit will occur at its vertex point. 
The vertex of a quadratic is given by: 

In this case, a = -1, b = 1280, and c = -3300. 
Then the point at which the maximum profit occurs is at: 

And the maximum profit will be: 
