While driving your rental car on your trip to Europe, you find that you are getting 10.4 kilometers per liter of gasoline. What does this correspond to in miles per gallon?

Answer 1

You can look these conversion factors up in tables or on Google. There are 3.785 L/gallon and 1.609 km/mile. So
10.6 km/L x (3.785 L/gallon) x (1 mile/km) = ?
Note that you makes these conversions so the unit you have gets canceled and leaves the units you want to keep. You see km in the numerator cancels with km in the denominator. Also L in the numerator cancels with L in the denominator. The units left are miles/gallon.