38 miles. Jodi's car drove 38 miles per gallon of gas.
To start, let's determine what we're looking for: miles traveled PER gallon of gas. We can replace "per" and say: miles traveled / gallons of gas.
If we fill in our new equation "miles / gallon" with the numbers given, we have: 456 miles / 12 gallons.
Solving this equation we get 38 miles / gallon.