Suppose That in a Random Sample of 30 Men, the Correlation

Suppose that in a random sample of 30 men, the correlation between hours spent working per week and hours spent playing with their children per week is -.50. The men in the sample spent an average of 50 hours per week working, with a standard deviation of 10. They spent an average of 6 hours per week playing with their children, with a standard deviation of 3. If you knew that one man spent 40 hours per week working, how many hours would you predict that he spent playing with his kids?