A certain car uses 12 gallons of gasoline in traveling 180 miles. In order for the car to travel the same distance using 10 gallons of gasoline, by how many miles per gallon must the car’s gas mileage be increased? Select:
A) 2	B) 3	C) 6	D) 8	E) 10

Rationale: "180 / 10 = 18 . the difference is 18 - 15 = 3 . answer b"
Answer: B