A company sells two sizes of microwave ovens: The small size and the large size. The demand functions for the microwave ovens are given by ps =150−0.5x−0.2y and pl =250− 0.1x−0.5 y , where ps and pl are the prices of the two sizes in dollars, x is the units of the small microwave ovens sold each week, and y is the units of the large microwave ovens sold each week.

(a) Determine the total revenue function R(x, y)



(b) Rx(50, 30)= .This number means that, when small microwave ovens and large microwave ovens are sold per week, if the sales of the small microwave ovens increase by 1 unit per week, and the sales of the large microwave ovens remain constant at units per week, then the total revenue increases by approximately $ per week.

(c) Ry(50, 30)= . This number means that, when small microwave ovens and large microwave ovens are sold per week, if the sales of the large microwave ovens increase by 1 unit per week, and the sales of the small microwave ovens remain constant at units per week, then the total revenue increases by approximately $ per week.