Respuesta :
[tex]\frac{3900}{5} = 780\sf ~kilometer~per~hour[/tex]
Your average speed is 780 kilometer per hour.
Your average speed is 780 kilometer per hour.
Your average speed is exactly 3900 km per 5 hours.
In more familiar units,
(3900 km) / (5 hr) = (3900/5) (km/hr) = 780 km/hr