An elevator in an office building made the following moves: Up 7 floors, down 14 floors, up 6 floors, down 2 floors, up 9 floors, down 5 floors. If the elevator stopped on the 54th floor, what floor did it start on?

It started on the 55th floor.

Step-by-step explanation:

We can work backwards from the 54th floor. Since we are working backwards, if the elevator goes up, we will subtract and if it goes down, we will add. Starting with 54, we get 54 + 5 = 59, then 59 - 9 = 50, then 50 + 2 = 52, then 52 - 6 = 48, then 48 + 14 = 62, then 62 - 7 = 55.