two boys starts from the same place walking at the rate of 4 kmph and 5.5 kmph respectively in the same direction . what time will they take to be 10.5 km apart ?
"explanation : relative speed = 5.5 - 4 = 1.5 kmph ( because they walk in the same direction ) distance = 10.5 km time = distance / speed = 10.5 / 1.5 = 7 hr answer : c"
divide(10.5, subtract(5.5, 4))