Joe quit his job in a bicycle shop, where he earned $15,000 per year, to become a graduate student in economics. At the university he attended, he spent $2,000 on books, $1,000 on aspirin, and earned $12,000 as an economics teaching-assistant. What were Joe's economic costs while attending college?

Brian has just finished college. he wants to set up a small business to make and sell fireworks. he registers his company and acquires a license from the government. he finds that most of his competitors are selling fireworks at an extremely low price. he would like to make more money, so he decides to innovate and develop better fireworks. he sells his fireworks at a higher price, and they are a huge hit with the customers. after a few years, he earns enough profit to set up a bigger fireworks factory that complies with the government’s health and safety regulations. he even starts exporting fireworks overseas. which type of economy does this scenario describe?