an escalator moves towards the top level at the rate of 15 ft . sec and its length is 200 feet . if a person walks on the moving escalator at the rate of 5 feet per second towards the top level , how much time does he take to cover the entire length .
"explanation : time taken to cover the entire length = tot . dist / resultant speed = 200 / ( 15 + 5 ) = 10 sec answer : b"
divide(200, add(15, 5))