Answer:
The answer is below
Explanation:
a) Let negative means the turtle position when descending and positive for going up. Therefore since the turtle was 850 meters below see level, it was at -850. It then moves 165 meters up, hence its new position is -685 meters (-850 + 165). Lastly it moves down 165 meters, hence its new position is -850 meters (-685 - 165)
b) The change in position is the sum of the movements = +165 - 165 = 0 meters.