When rates are expressed as a quantity of 1, such as 2 feet per second or 5 miles per hour, they are called unit rates.To find the unit rate, divide the numerator and denominator of the given rate by the denominator of the given rate
Given :3 gallons of milk cost $9.87
To find the unit rate we find the cost of 1 gallon of milk.
Cost of 1 gallon of milk= $9.87÷3 =$3.89.
The unit rate is $3.89.