The other tutor obviously doesn't know linear algebra. He thought you were taking stats. The first part of your problem is just like this problem on this Youtube video: http://www.youtube.com/watch?v=QkepM8Vv3kw Find the regression line for your 4 points using that method. Then take the two other equations with this regression equation and find the linear regression of the three equations just like this video: http://www.youtube.com/watch?v=8mAZYv5wIcE Edwin