Tesla Inc. currently sells 30,000 Model X cars per year at $70,000 each and 15,000 Model Y per year at $120,000 each. The company wants to introduce a new line - Model Z - to fill out its product line; it hopes to sell 25,000 of these Model Z cars per year at $20,000 each. An independent consultant has determined that if Tesla introduces the Model Z, it should boost the sales of its existing Model X cars by 2,700 units per year and reduce the sales of its Model Y by 1,300 units per year. What is the amount to use as the annual sales figure when evaluating this project? Why?