TS ICET 27 May 2023 Shift 2 Solved Paper

A boat can cover $54\mathrm{km}$ in still water in 6 hours. It can cover $210\mathrm{km}$ upstream and the same distance in down stream in a total of 48 hours. Then the difference of times taken by the boat to cover $72\mathrm{km}$ upstream and to cover $63\mathrm{km}$ down stream (in hours) is