On his way home from the school board meeting, Keith fills up his car. He likes the idea of using gasoline with ethanol, but thinks his car can only handle 40% ethanol. At the gas station, he can use regular gas with 10% ethanol or E85 fuel with 85% ethanol. How many gallons of each type of fuel should Keith use if he wants to fill up his car with 10 gallons of fuel containing 40% ethanol?