A regression was run to determine if there is a relationship between hours of TV

A regression was run to determine if there is a relationship between hours of TV watched per day (x) and number of situps a person can do (y).
The results of the regression were:
y=ax+b
a=-0.907
b=32.986
r2=0.471969
r=-0.687
Use this to predict the number of situps a person who watches 5.5 hours of TV can do (to one decimal place)