7. A hot air balloon is descending in the sky at a rate of 2 meters per second. An observer, 30 meters away from where the balloon is, watches as the balloon descends. At what rate is the angle of elevation from the observer to the balloon changing when the balloon is 15 meters above the ground? Show all work in deriving your answer. Leave answer as a fraction or a decimal rounded to three decimal places. observer 30 m balloon