Answer:
155 feet
Explanation:
the building is 85 feet high that's where drone starts
the drone flies to 120 feet in 10 seconds from 85 feet so the rate equals 35 feet per 10 second
in 20 seconds the drone would be 70 feet higher.
so the final height would be 85 feet plus 70 feet which equals 155 feet.
hope that helps