Answer: -2500 feet or 2500 feet down.
Explanation:
Given : A mountain descends a mountain for 5 hours.
On average, she climbs down 500 feet each hour.
Since , we use negative sign to represent down or descend in quantity in integers.
Thus IN INEGERS, on average, she climbs -500 feet each hour.
Now, her change in elevation after 5 hours will be :-

Hence, her change in elevation after 5 hours= -2500 feet.