In Dangjin, South Chungcheong Province, Song-tae Choi, who has been cultivating apples for 40 years, had the best year ever. This is because he achieved the highest income in his 40-year farming career. He generated 100 million won in sales from 510 pyeong of land with 180 trees, which is less than 200 trees. If converted to sales per tree, it amounts to approximately 550,000 won per tree. How many apples did he harvest to achieve a profit of 550,000 won per tree? According to the fruit tree survey from the Crop Disaster Insurance, the minimum number of apples per tree was 170, while Choi himself counted up to a maximum of 280. On average, it is said that about 250 apples were harvested per tree.