An elevator starts on the ground floor. It goes up 7
floors and then down 9 floors.
What floor is it on?

Two floors underground

Step-by-step explanation:

-2nd level, in the basement

Step-by-step explanation:

If we look at the number line, we can track the movement of the elevator. The ground floor is point 0. The blue dot indicates the starting position. The blue arrow indicates the positive movement of 7, and the red arrow shows negative movement of 9. The red dot is the elevator's final position.

I hope this helps!

-2

7 - 9 = -2

reversed:

-2 + 9 = 7