Suppose that there is asymmetric information in the market for used cars. Sellers know the quality of the car that they are​ selling, but buyers do not. Buyers know that there is a 50​% chance of getting a​ "lemon", a low quality used car. A high quality used car is worth​ $30,000, and a low quality used car is worth​ $15,000. Based on this​ probability, the most that a buyer would be willing to pay for a used car is ​$________. ​(Enter your response rounded to the nearest​ dollar.)