Answer:
The net change would be -2.
Step-by-step explanation:
The upward change of elevator is represented by positive sign while the downward change represented by negative sign.
Given,
First the elevator goes up 15 floors,
change = + 15,
Then it goes 9 floors down,
change = -9,
Then it goes 11 floors up,
Change = + 11,
Finally, it goes 19 floor down,
Change = - 19
So, the net change = sum of total changes = 15 - 9 + 11 - 19 = -2
