An elevator went up 15 floors, down 9 floors, up 11 floors and down 19 floors. find the net change

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

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