The pilot of a small aircraft with a 40-gallon fuel tank wants to fly to Cleveland, which is 480 miles away. The pilot recognizes that the current engine, which can fly only 6 miles per gallon, will not get him there. By how many miles per gallon must the aircraft’s fuel efficiency be improved to make the flight to Cleveland possible? Choose the most appropriate option:
A) 2  B) 4  C) 12  D) 6  E) 160

Rationale: "actual miles / gallon is = 480 / 40 = 12 miles / gallon . current engine miles / gallon is 6 miles / gallon . additional 6 miles / gallon is required to match the actual mileage . imo option d ."
Answer: D