My statistics book says the following: Linear Regression If the regression equation for the depression screening example was Y=0.

Hi. My statistics book says the following:

Linear Regression

If the regression equation for the depression screening example was Y=0.40 + 10(X), then a score of 20 on the screening test (X) would lead to a predicted score on the criterion of 3.0, meaning mild depression. Likewise, a minimum possible score of ) on the screening test would lead to a predicted criterion score of 0.40 (little to no depression), and a maximum possible score of 50 on the screening test would lead to a predicted criterion score of 6.9, indicating severe depression.

I get how they got the 0.40 when plugging in the numbers, but how did they get the 3.0 and 6.9? Please explain.

Thank you very much.