bearing in mind that the average rate of change is the slope, then we can pick any two points from the table to get the slope,
[tex]\bf \begin{array}{ccll}
\stackrel{time}{hours}&\stackrel{distance}{miles}\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
4&212\\
\boxed{6}&\boxed{318}\\
8&424\\
\boxed{10}&\boxed{530}
\end{array}\qquad \qquad \qquad
(\stackrel{x_1}{6}~,~\stackrel{y_1}{318})\qquad
(\stackrel{x_2}{10}~,~\stackrel{y_2}{530})[/tex]
[tex]\bf slope = m\implies
\cfrac{\stackrel{rise}{ y_2- y_1}}{\stackrel{run}{ x_2- x_1}}\implies \cfrac{530-318}{10-6}\implies \cfrac{212}{4}\implies \cfrac{\stackrel{miles}{53}}{\stackrel{hours}{1}}[/tex]
