$A$ boat goes $13\, km$ upstream in $39\, minutes$. The speed of the stream is $3\, km/h$. The speed of the boat in still water is......$km/h$.

$A$ boat covers a certain distance downstream in $2$ $hours$,but takes $4$ $hours$ to return upstream to the starting point. If the speed of the stream is $3$ $km/h$,find the speed of the boat in still water (in $km/h$).

$A$ man can row $15\, km$ downstream in $3\, hours$ and $5\, km$ upstream in $2.5\, hours$. His speed in still water in $(km/hr)$ is:

$A$ boatman rows $1\, km$ in $5\, min$ along the stream and $6\, km$ in $1\, h$ against the stream. The speed of the stream is in $km/h$:

Speed of a motorboat in still water is $45\, km/h$. If the motorboat travels $80\, km$ along the stream in $1\, h\, 20\, min$,then the time taken by it to cover the same distance against the stream will be:

The speed of a boat in still water is $6\, km/h$. It takes the boat twice as long to row up as to row down the river. Find the rate of the stream (in $km/h$).