two trains of length 200 m and 300 m are 200 m apart . they start moving towards each other on parallel tracks , at speeds 36 kmph and 72 kmph . in how much time will the trains cross each other ?
"relative speed = ( 36 + 72 ) * 5 / 18 = 6 * 5 = 30 mps . the time required = d / s = ( 200 + 200 + 300 ) / 30 = 700 / 30 = 70 / 3 sec . answer : d"
divide(200, multiply(add(36, 72), const_0_2778))