Doug purchases a 25% interest in the Hay Partnership for $20,000 on January 1, 2010, and begins to materially participate in the partnership's business. The Hay Partnership uses the calendar year as its tax year. At the time of the purchase, the Hay Partnership has $2,000 in liabilities, and Doug's share is 25%. During the year, the Hay Partnership incurs $100,000 in losses and its liabilities increase by $4000. What is Doug's basis in his partnership interest on December 31, 2010?