$A$ man can row $30 \text{ km}$ downstream and return in a total of $8 \text{ h}$. If the speed of the boat in still water is $4$ times the speed of the current,then the speed of the current is ....... $\text{km/h}$.

Rohit can row a certain distance downstream in $8$ $hours$ and return the same distance in $12$ $hours$. If the stream flows at the rate of $5$ $km/hr$,find the speed of Rohit in still water (in $km/hr$).

In a river,the ratio of the speed of the stream to the speed of a boat in still water is $2:5$. In another case,the ratio of the speed of the stream to the speed of a boat in still water is $3:4$. What is the ratio of the speeds of the first boat to the second boat in still water?

$A$ motor-boat,travelling at the same speed,can cover $25\, km$ upstream and $39\, km$ downstream in $8\, hours$. At the same speed,it can travel $35\, km$ upstream and $52\, km$ downstream in $11\, hours$. The speed of the stream is $........\, km/h$.

$A$ motorboat travelling at some speed can cover $25\, km$ upstream and $39\, km$ downstream in $8\, h$. At the same speed,it can travel $35\, km$ upstream and $52\, km$ downstream in $11\, h$. The speed of the stream is........$km/h$.

$A$ boat goes $2\, km$ upstream and $3\, km$ downstream in $20$ minutes. It goes $7\, km$ upstream and $2\, km$ downstream in $53$ minutes. What is the speed (in $km/hr$) of the boat in still water?