A person has to board a train from the railway station at 9:30 am. He leaves for the station from his home by car at 8 am at a speed of 40 km/hr. At about 8:15 am, he realises that, he had forgotten his reserved train ticket at home. At what speed shall he drive his car so that after taking his ticket from home, he can reach the station on time? The distance between railway station and his house is 60 km.