The equations x+5x=16 and x+5x+25=16 No, the equations are not equal. In order for an equation to be equal the equation x+5x=16 contains 25 less than the second equation.
List 1 mentions that there is "Ham, Carrots, celery". We know that students can only have <em>either </em>carrots or celery, but the list shows that the students have both. Therefore, list 2 is correct.
A plot of residuals (vertical deviations from the regression line) shows the errors or lack of fit, so it would indicate a good fit if the residuals are small, vs. over fit if they are large. Due to age related growth short pre teen, and a plateau after age 21, I would expect a linear regression would offer estimate age 5.5 years.