If the operating cost of 6 burners for 6 hours in 8 days is Rs. 450 then find the number of burners if used for 5 hours for 10 day with operating cost of Rs.1250.
The speed of a boat in still water is 18 km/h and the speed of the current is 6 km/h. In how much time (in hours) will the boat travel a distance of 90 km upstream and the same distance downstream?