Suppose you own and operate a coffee shop in your hometown. Each year, you receive revenue of $200,000 from coffee sales, and it costs you $100,000 to obtain your raw materials. In addition, you pay $20,000 for electricity, taxes, and other expenses per year. Instead of running the coffee shop, you could become an accountant and receive a yearly salary of $40,000. A clothing retailer, interested in expanding, has also offered to rent your shop space from you for $50,000 per year. How do you explain to your friends that despite making a profit, it is too costly for you to continue running your shop?