Answer:
3,000 meters.
Explanation:
What you should first do is set up a diagram to demonstrate the velocity of the balloon and wind.
After having that set up, you can use the pythagorean theorem to find the hypotenuse of the triangle made after 10 seconds.
3²*10²=√900 (for one second)
√900 = ±30 m traveled in one second
30²×100²=√9,000,000
√9,000,000 = ±3,000 m