The speed of a boat in still water is $7\, km/h$. If its speed in downstream is $10\, km/h$,then the speed of the stream is .......... $km/h$.

Speed of boat in still water is $5\, km/h$. While river is flowing with a speed of $2\, km/h$ and time taken to cover a certain distance upstream is $2\, h$ more than time taken to cover the same distance downstream. Find the distance (in $km$).

$A$ man can row at the rate of $3.5 \, km/h$ in still water. If the time taken to row a certain distance upstream is $2 \frac{1}{2}$ times as much as the time taken to row the same distance downstream,find the speed of the current in $km/h$.

$A$ boat running downstream covers a distance of $20\, km$ in $2\, h$ while it covers the same distance upstream in $5\, h$. Then,the speed of the boat in still water is ....... $km/h$.

What time will be taken by a boat to cover a distance of $128\, km$ along the stream,if the speed of a boat in still water is $24\, km/h$ and the speed of the stream is $8\, km/h$? (in $h$)

Speed of a man is $12 \text{ km/h}$ in still water. If the rate of current is $4 \text{ km/h}$,then the effective speed of the man upstream is ......... $\text{km/h}$.