A car covers 15 km, 20 km, 30 km and 12 km at speeds of 20 km/hr, 30 km/hr, 40 km/hr and 30 km/hr respectively The average speed of the car for the total journey is:
Two cars travel from city A to city B at speeds of 42 km/hr and 60 km/hr respectively. If one car takes 2 hours lesser time than the other car for the journey, then the distance between city A and city B is?