Jamal quits a job that was paying him $30,000 per year and decides to start his own business. He runs his business out of his house in a room he had been renting to his colleague for $12,000 a year. Jamal withdraws the $20,000 in his saving account that had been earning him a 10 percent annual interest to purchase computers and related accesaories and equipment for the business. During the first year of operation, Jamal's business incurred $30,000 in explicit costs and generated $60,000 in total sales. Jamal's economic profit is what?