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Home > CC1 > Chapter 7 > Lesson 7.3.4 > Problem 7-123

7-123.

ELEVATOR CHALLENGE

Juan got on an elevator at the middle floor of a building, went up floors, down floors, up floor, and down floors, where he left the elevator on the ground floor. Homework Help ✎

  1. How many floors are in the building?

    First, draw a vertical number line and pick a tick mark to represent the middle floor.

    Then trace his path, starting at the middle floor and move floors up.

    Then move floors down.

    Next, move floor up.

    Last, move floors down to the ground floor.

    If you stop on the first floor and there are seven floors below the middle floor, there should be floors above. How many floors are there?

  2. Explain how you found the number of floors.

    Did you work backwards?
    Or did you set up a number line?