A 20-foot ladder is leaning against a building. If the bottom of the ladder is sliding along the pavement directly away from the building at 2 ?feet/second, how fast is the top of the ladder moving down when the foot of the ladder is 3 feet from the? wall?The top of the ladder is moving down at a rate of _____ ?feet/second when the foot of the ladder is 3 feet from the wall. ?(Round to the nearest thousandth as? needed.)