Suppose that a ladder of length 25 ft is placed on a vertical wall. It was then found out that the foot of the ladder slides at a rate of 2 in/min. How fast is the top of the ladder sliding down at an instance when the foot of the ladder is 20 feet away from the wall? A -2/9 ft per min В -4.5 ft per min -3.5 ft per min -1/8 ft per min