$A$ 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 $km$).

Speed of a boat in standing water is $9 \text{ km/h}$ and the speed of the stream is $1.5 \text{ km/h}$. $A$ man rows to a place at a distance of $105 \text{ km}$ and comes back to the starting point. The total time taken by him is (in $\text{ hours}$)

$A$ man can row at $5 \, km/h$ in still water. If the velocity of the current is $1 \, km/h$ and it takes him $1 \, h$ to row to a place and come back,how far is the place? (in $km$)

$A$ man can row $7\, km/hr$ in still water. If the river is running at $3\, km/hr$,it takes $6\, hours$ more to row upstream than to row downstream for the same distance. How far is the place? (in $km$)

The current of a stream runs at $1 \, km/h$. $A$ motor boat goes $35 \, km$ upstream and back again to the starting point in $12 \, hours$. The speed of the motor boat in still water in $km/h$ is:

$A$ man can row $6 \, km/h$ in still water. If the speed of the current is $2 \, km/h$,it takes $3 \, h$ more in upstream than in the downstream for the same distance. The distance is......$km$.