Question 1

what is the opportunity cost? for instance, A works as teacher and earning $180,000. A enjoys teaching, drinking French wine. However someday he got an offer from a large company, this company offers him an annual salary of $750,000 to leave school and take up a position as a senior consultant. If A continues working at the school, what is the opportunity cost of his decision?

Please explain to me how can we find/count the opportunity cost?

Question 2

Please explain to me about what is zero economic profit? since A loves wine, he decided to buy a vineyard from his savings. So, how much annualfinancialprofit does A need to earn in order to make zeroeconomicprofit?

I got confused on how we count the zero economic profit.