A boat covers $122.5$ km distance downstream at $30$ kmph and $240$ km upstream at $6$ kmph. If the speed of the boat and the speed of the stream are increased by $11\frac{1}{9}\%$ and $25\%$, respectively, then what is the total time taken by the boat to cover the same distance upstream and downstream?

Ratio between speed of boat in still water to speed of stream is $8:1$.If $67.5$ kms is travelled downstream in $2.5$ hours then find the difference between speed of boat in still water to speed of stream?

Quantity $1$: Ratio between the speed of the boat in still water to the speed of the stream is $2:1$. Total time taken by a man to cover distance of $72$ km in upstream and comeback is $32$ hours. Find downstream speed.

Quantity $2$: $9$ $9 \mathrm{km}/\mathrm{h}$.

A boat in still water takes $15$ hours to reach its destination and come back from there. In the same river, it takes $16$ hours for the same journey where there is a current in the water. The difference between the speed of the boat and the river current is $15$ $km/hr$. Find out the speed of the river?

Speed of a boat along with the current and against the current are $12$ km/hr and $6$ km/hr respectively. What is the speed of the boat (in km/hr) in still water?