[tex]\begin{gathered} \text{rate of change = }\frac{\Delta\text{miles}}{\Delta gallons}\text{ = }\frac{160-64}{5-2} \\ =\frac{96}{3}\text{ = 32miles/gallon} \end{gathered}[/tex]
Taking two points on the graph
when miles = 160 , gallon = 5
when miles = 64 , gallon = 2
