In the study of the effect of secondhand smoke on the relationship between Martian weight and height in Fig. 3-7A, exposure to secondhand smoke shifted the line down in a parallel fashion as described...

In the study of the effect of secondhand smoke on the relationship between Martian weight and height in Fig. 3-7A, exposure to secondhand smoke shifted the line down in a parallel fashion as described by Eq. (1.3). If secondhand smoke affected the slope as well as the intercept, the lines would not be parallel. What regression equation describes this situation?

Fig. 3-7A

Eq. (1.3)