Answer
Slope = 1.033; The numerical value of the slope indicates that, on average, for every one unit increase in city mpg, highway mpg is expected to increase by 1.033.
Work Step by Step
To identify the slope of the regression line, use the following equation: y = a + b(x), where y is the predicted y value for a given value of x; a is the intercept; and b is the slope.
Reworking the given regression line to fit this structure we have y = 6.78 + 1.033 (x). This means that the slope(b) is equal to 1.033.