Problem: two trains of length 100 m and 200 m are 100 m apart . they start moving towards each other on parallel tracks , at speeds 54 kmph and 90 kmph . in how much time will the trains cross each other ?
Rationale: "a relative speed = ( 54 + 90 ) * 5 / 18 = 8 * 5 = 40 mps . the time required = d / s = ( 100 + 100 + 200 ) / 35 = 400 / 40 = 10 sec ."
annotated_formula: divide(100, multiply(add(54, 90), const_0_2778))