Pria bought a new car that advertised an estimated gas mileage of 35 miles per gallon. The car has a 12-gallon tank. She filled her car full of gas and was able to drive a total of 372 miles. What was the difference, in miles per gallon, between Pria's mileage and the advertised mileage?
Pria's car achieved a rate of 372 miles / 12 gallons = 
<gadget id="calculator">372/12</gadget>
<output>31</output>
31 miles per gallon.
Therefore, it was a difference of 35 - 31 = 
<gadget id="calculator">35-31</gadget>
<output>4</output>
4 miles per gallon.

<result>4</result>