The multiple regression equation for the carbon monoxide content with known tar and nicotine content (all in milligrams) for US cigarettes is

y = 3.6738 + 1.2874x1 - 7.531x2

where x1 is the amount of tar content and x2 is the amount of nicotine (in milligrams)

Predict the carbon monoxide content for a cigarettewith 12 milligrams of tar and 0.9 milligrams of nicotine.