how to solve

Next A regression was run to determine if there is a relationship between hours of TV watched per day, I, and number of sit-ups, y, a person can do in a minute. The results of the regression were: y=ax+b a=-0. 707 b=20 . 152 Use this to predict the number of sit-ups a person who watches 12 hours of TV can do in a minute. Round to the nearest whole number