Question 839351
Consider the units of each number.
{{{Gallons/Population}}} will be in units of Gallons per Person.


Think of the arrangement of the expression to compute this way:
(How much is consumed)/(How many people consume it);


For using the site's rendering to help you see this in more conventional way,
{{{(HowMuchIsConsumed)/(HowManyPeopleConsumeIt)}}}