An investor, who had $75,000 to contribute, was choosing between a boutique and a local shoe shop. After careful deliberation, the investor chose the boutique. In the first year, the boutique generated enough profit to pay the investor $15,000 (an agreed percentage of profits to be paid to the investor). The investor found out that if he had invested in the local shoe shop he would have received $9,000 (an agreed percentage of profits to be paid to the investor). The investor's economic profit was