An elevator traveled in this way: up 18 floors, down 6 floors, down 14 floors, up 19 floors, down 25 floors. what was the net change in position of the elevator?

18 - 6 - 14 + 19 - 25 = -8
The elevator went down 8 floors.

18 - 6 - 14 +19 -25 = -8
The elevator then moved down 8 floors
Also, you notice a pattern in the wording : up, down,down,up,down 
Therefor the next movement would be down