Answer:
6 ft above ground.
Explanation:
The roller coaster starts from an elevation of +20 feet from the ground.
Now, it first corns 78 ft, then drops 85 ft.
So, the final elevation will be (20 + 78 - 85) = 13 feet above the ground on the second hill.
Again, it climbs 103 ft. and drops 110 ft. and finally his elevation will be = 13 + 103 - 110 = 6 ft above ground. (Answer)