Hello, could you help me to solve this problem?

Hello, could you help me to solve this problem? Thank you very much.

Over winter break, Matthew returned home and celebrated the holidays with his extended family. With all of the rich meals he enjoyed at several holiday feasts, and the plentiful snacks while watching football games, he gained 5 pounds in twenty-one days. On average, how many Calories per day did he consume in excess of his body's needs?