(20%)(4) The following results were obtained from a multiple regression analysis of supermarket profitability. The dependent variable, y, is the profit (in thousands of dollars) and the independent variables, x1 and x2, are the food sales and nonfood sales (also in thousands of dollars).

| | ANOVA Table | |
| --- | --- | --- |
| | df | SS |
| Regression | - | 562 |
| Residual | 9 | 225 |
| Total | | |

| | Coefficients | Standard Error |
| --- | --- | --- |
| Intercept | -15.06 | |
| x1 | 0.10 | 0.05 |
| x2 | 0.25 | 0.09 |

a. Write the estimated regression equation for the relationship between the variables.