Deepa rides her bike at an average speed of 30 km/hr and reaches her destination in6 hours. Hema covers the same distance in 4 hours. If Deepa increases her average speed by 10 km/hr and Hema increases her average speed by 5 km/hr what would be the difference in their time taken to reach the destination? `40\ m inu t e s` b. `45\ m inu t e s` c. `4\ m inu t e s` d. `1\ hou r` e. none of these