Answer:
Rate per gallon in simplest form is, 
Step-by-step explanation:
Unit rates defined as the rates are expressed as a quantity of 1, such as 5 feet per second or 6 miles per hour, they are called unit rates.
Given the statement: 252 miles per 8 gallons.
⇒ Number of miles = 252
and number of gallons = 8
Unit rate per gallons =
=
Divide numerator and denominator both by 4 we get;
Unit rate per gallons = 
Therefore, "252 miles per 8 gallons " as a rate in simplest form is, 