Upon graduating with an accounting degree, you open your own accounting firm of which you and your assistant are the only employees. To start the firm you passed on a job offer with a large accounting firm that offered you a salary of \( \$ 50,000 \) annually. Last year you earned a total revenue of \( \$ 120,000 \). Rent and supplies last year were \( \$ 50,000 \). Your assistant's salary is \( \$ 30,000 \) annually.
Your annual economic profit is
a. \( \$ 40,000 \).
b. \( -\$ 10,000 \).
c. \( \$ 70,000 \).
d. \( \$ 20,000 \).