c) (4 pts) Using the cost C=100x* +800 and revenue R =4x , define an equation for the average profit function. Also display a graph of the average profit function with settings Xmin=0, Xmax=10, Ymin= -50, Ymax=50, and use that display to estimate the breakeven point (x value at which average profit 2 0 ). Then analytically evaluate the rate of change at that point