Final answer:
The slope of the regression line is 0.993.
Step-by-step explanation:
The regression line that relates the highway gas mileage to the city gas mileage is given by the equation: highway mpg = 7.903 + 0.993 × city mpg. The slope of a regression line represents the change in the dependent variable (highway mpg) for a one-unit increase in the independent variable (city mpg). In this case, the slope of the line is 0.993. This means that for every one-unit increase in the city mpg, we expect the highway mpg to increase by approximately 0.993 units.