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?
Please reason step by step, and put your final answer within \boxed{}.
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