David runs his own business. He received an offer from a company for $50,000 per year. If he sells his business, he can get an amount of $100,000. Assume the annual interest rate is 5%. David is confused to run his business or join the company. David annual revenue from his business is enough to cover all explicit cost and has $60,000 left over. There are no additional implicit costs. Calculate David's accounting and economic profit?