Water flows from a tank of constant cross-sectional area 80 ft through an orifice of constant cross-sectional area ft located at the bottom of the tank. Initially, the height of the water in the tank was 20 ft, and its later t was given by the equation 2/h +11-2/20 = 0 0sts 80/20. How fast (in ft/s) was the height of the water decreasing when its height was 9 ft? ft/s