slope and maximum height of curve

This problem gives you a preview of something you might see in a microeconomics dass, Suppose there's an appliance store that sells dishwashers. It could set its price high and sell very few dishwashers, or it could set its price low and sell many more dishwashers, The following table shows some possible choices this store could make! Price Quantity Total Revenue (P = Q) (Dollars per dishwasher) (Dishwashers per year) (Dollars per year) 400 300 120 36,090 200 240 48,000 100 36,00-0The graph below plots the firm's total revenue curve: that is, the relationship between quantity and total revenue given by the two right columns in the table above. The five choices are also labeled. Finally, two black lines are shown; these lines are tangent to the green curve at points B and D. GO C 120, 36 TOTAL REVENUE (Thousands of dollars per year) 30 GO 120 160 240 QUANTITY (Dishwashers per year)Using the information on the slope of the lines tangent to the curve at points Il and D, plot the slope of the total revenue curve on the graph below. (As it turns out, it's a straight line, so the two points you plot will determine a line.) 200 Skipn of TH REVENUE (Delorper dishwasher) TOE 120 180 240 300 30 480 QUANTITY (Dishwashers per year) The total revenue curve reaches its maximum at a quantity of . dishwashers per year. At this point, the slope of the total revenue curve is