Two algebra teachers are on a plane. Shortly after reaching cruising altitude, one of the engines conks out. However, the flight attendant announces that the plane has three other engines. However, instead of needing 3 hours to fly to their destination on 4 engines, it will now take 4 hours to fly on 3 engines.
A little while later, another engine goes out. Never fear, says the flight attendant: the plane can fly on two engines. Unfortunately, the length of the flight has now increased to 6 hours.
Later still, a third engine fails. Not to worry, says the flight attendant. The plane can fly on only one engine. But the flight will now last 12 hours.
So one algebra teacher says to the other, “I really hope that last engine doesn’t go out, or else we’ll be up here forever!”
Mean Green Math 