A 124-kg balloon carrying a 22-kg basket is descending with a constant downward velocity of 20.0 m>s. A 1.0-kg stone is thrown from the basket with an initial velocity of 15.0 m>s per- pendicular to the path of the descending balloon, as measured relative to a person at rest in the basket. That person sees the stone hit the ground 5.00 s after it was thrown. Assume that the balloon continues its downward descent with the same constant speed of 20.0 m>s. (a) How high is the balloon when the rock is thrown