The graph below shows the #tal distance, in miles, traveled by a towboat over time,
 in hours.
 AVERAGE SPEED
 OF TOWBOAT
 21.00
 Total Distance (miles)
 15.75
 10.50
 5.25
 0 1 2 3 4
 Time (hours)
 Which statement best describes the meaning of the coordinates of point Fon
 the graph?
 It shows the unit rate of the graph in hours per mile