The ratio of the speed of boats ‘A’ and ‘B’ in still water is 8:9, respectively. The speed of the current is 25% of the speed of boat ‘A’ in still water. If boat ‘A’ takes 12 hours to travel 600 km downstream, then find the time taken by boat ‘B’ to travel 140 km upstream and 550 km downstream. (Note: Both the boats are rowing in the same stream.)