$A$ 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 $km/h$:

$A$ swimmer covers a distance of $28\, km$ against the current and $40\, km$ in the direction of the current. If in each case he takes $4\, hours$,then the speed of the current is..........$km/h$.

$A$ man can row upstream $36 \text{ km}$ in $6 \text{ hours}$. If the speed of a man in still water is $8 \text{ km/hr}$,find how much distance he can cover downstream in $10 \text{ hours}$? (in $\text{km}$)

$A$ steamer goes downstream from one port to another in $4\, h$. It covers the same distance upstream in $5\, h$. If the speed of the stream is $2\, km/h$,then find the distance between the two ports (in $km$).

Two boats $A$ and $B$ start towards each other from two places,$108 \text{ km}$ apart. The speeds of boats $A$ and $B$ in still water are $12 \text{ km/h}$ and $15 \text{ km/h}$,respectively. If $A$ proceeds down the stream and $B$ proceeds up the stream,they will meet after .......... $\text{h}$.

$A$ boat goes $48\, km$ downstream in $20\, h$. It takes $4\, h$ more to cover the same distance against the stream. What is the speed of the boat in still water? (in $km/h$)