Does anyone know the answer to this math problem?

1. Working alone, Holmes puts two coats of paint on a wall, one before and one after lunch. One day, Homes began at the usual time. Two hours before lunch he was joined by Watson, who paints at the rate of 600 m^2 each workday, and who left when the 1st coat was finished. Holmes promptly began the 2nd coat and had lunch at the usual time. One hour before his normal quitting time, Holmes had painted a 2nd coat everywhere except where Watson had painted the morning. If each man's normal workday is the same and if each works at a constant rate, what was the area of the wall in m^2?