Answer:
After 5 minutes the two balloons will be at the same height.
Explanation:
Let, the two balloons will be at the same height after t minutes.
Then, according to the question,
15 + 20t = 195 - 16t
⇒ 36t = 180
⇒ t =

⇒ t = 5
So, after 5 minutes the two balloons will be at the same height.