Victor Murray’s firm manufactures scientific graphing calculators that cost $40 each to produce and business calculators that cost $20 each.

a. If x graphing calculators and y business calculators are produced each month, express the total monthly cost of production as a function of x and y.

b. Compute the total monthly cost if 500 graphing calculators and 800 business calculators are produced.

c. Victor wants to increase the output of graphing calculators by 50 each month from the level in part (b) but wants the total cost of production to remain the same. What change should he make in the monthly production of business calculators to achieve this goal?