The elevation at ground level is 0 feet. An elevator starts 90 feet below ground level. After traveling for 15 seconds, the elevator is 20 feet below ground level. Did the elevator travel up or down? What was the speed (in ft per second) of the elevator in the 15 second interval? This is due at 8am tomorrow please help me

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.

:)))

The 8th term is 512