The answer is -4 2/3
Explanation : The elevator is at 0, and went below ground level 90 feet, that would be -90, then it went up 20 feet, which would be -90 + 20 = -70
-70 ft / 15sec = - 4 2/3
I am not sure about the ground level and negative difference but that it is what I was taught. Below ground level is negative and above is positive. Therefore the elevator traveled up and it traveled -4 2/3 per second.
It so either 4 2/3 or - 4 2/3 but pretty sure it is - 4 2/3.
:)))
