The word "per'' is a signal that it's time to do division. It means roughly "for every." Think to yourself, "For every numerator there is a denominator." We're sorry we don't have this for you in acronym form, unless FENTIAD helps you somehow.
Luisa drove 150 miles and used 6 gallons of gas. How many miles per gallon does her car get? Also, when will she start caring about the environment and go electric?
To find the number of miles per gallon, we take the number of miles divided by the number of gallons:
so Luisa's car gets 25 miles per gallon. Oh, good. She can keep driving away from the Earth's problems.