Suppose you were interested in the relationship between years of education and income. You find that the constant is 12,000, the coefficient of determination is 0.29 and that the regression coefficient is 8,000. However, you add age to the model and find that the constant is now 6,000, the regression coefficient for education is 4,000 and the regression coefficient for age is 800. What is the multiple regression formula describing this model? [short response]