Graph should represent "miles per gallon" that means the y axis are miles driven with x axis gallons used.
See image attached.
The fuel usage is approximately linear so the graph is a line. The origin of the graph (0,0) corresponds to the starting point in MIami, FL, where 0 gallon have been spent and 0 miles driven. the endpoint corresponds to Atlanta, GA, where 90 gallons have been spent and 660 miles driven. The domain is real numbers in the interval [0,90]. The x intercept is 0, the y intercept is also 0. The range is real numbers in the interval [0,660].
