suppose you deliver mail in an office building. You leave the mailroom and enter the elevator next door. you go up 4 floors, down 7, and up nine to the top floor. Then,you go down 6, up 2 and down 8 to the lobby on the first floor. What floor is the mailroom on?
from mailroom at floor x :
x + 4 - 7 + 9 - 6 + 2 - 8 = 1
x = ....
To determine the floor where the mailroom is located, we need to keep track of the net movement in terms of floors. Let's go step-by-step:
1. Starting from the mailroom floor, you go up 4 floors.
2. Next, you go down 7 floors, which will bring you 3 floors below your starting point.
3. Then, you go up 9 floors, compensating for the previous descent and reaching 6 floors above your starting point.
4. Moving on, you go down 6 floors, which brings you back to +3 floors from the starting point.
5. After that, you go up 2 floors, increasing your position to +5 floors.
6. Finally, you go down 8 floors, which takes you to -3 floors from the starting point.
7. Finally, you reach the lobby on the first floor, which is the same as being at -3 floors.
Thus, the mailroom is located on the 3rd floor below the lobby, which is the 4th floor counting upwards from the first floor.