An airplane flew 9000 km from Country X to Country Y at a speed of 450 km/h. It then covered 4900 km from Country Y to Country Z at a speed of 350 km/h. Find the time taken for the whole journey.
A lorry and a bus were travelling from town A to town B which were 720 km apart. The bus set off 2 12 h later than the lorry but arrived 1 12 h earlier. If the average speed of the lorry was 60 km/h, find the average speed of the bus.