Please show your work:

7. Division P of Turbo Corporation has the capacity for making 75,000 wheel sets per year and regularly sells 60,000 each year on the outside market. The regular sales price is $100 per wheel set, and the variable production cost per unit is $65. Division Q of Turbo Corporation currently buys 30,000 wheel sets (of the kind made by Division P) yearly from an outside supplier at a price of $90 per wheel set. If Division Q were to buy the 30,000 wheel sets it needs annually from Division P at $87 per wheel set, the change in annual net operating income for the company as a whole, compared to what it is currently, would be: A. $600,000 B. $225,000 C. $750,000 D. $135,000