Consider the price of gas in France to be 1.3 euros per liter. If a visitor has 50 euros, how many gallons can be purchased (there are 4 quarts per gallon and a liter is ~ 1 quart) ?

10.16 gallons of gas

Explanation:

To be exact, a US gallon contains 3.78541 liters.

So a gallon of gasoline contains 3.78541 liters of gasoline, which means that one gallon of gasoline costs 1.30€ x 3.78541 = 4.92€

If the visitor has 50€, he/she can purchase 50€/4.92€ = 10.16 gallons of gas

*Only the US, Myanmar and Liberia use the imperial system of measurement (e. g. miles, yards, feet, gallons, quarts, etc.) while the rest of the world uses the metric system (e. g. meters, kilometers, liters, etc.). But the US was one of the first countries in the world to formally adopt the metric system (since the 19th century), but the change was not mandatory, so most people continued to use the imperial system as part of the culture.