The speed of a boat in still water is $9\, km/h$ and the speed of the stream is $1.5\, km/h$. $A$ man rows to a place at a distance of $105\, km$ and comes back to the starting point. What is the total time taken by him?

$A$ boat can travel with a speed of $13\, km/hr$ in still water. If the speed of the stream is $4\, km/hr,$ find the time taken by the boat to go $68\, km$ downstream. (in $hours$)

$A$ man can row at $10 \text{ km/h}$ in still water. If he takes a total of $5 \text{ h}$ to go to a place $24 \text{ km}$ away and return,then the speed of the water current is $... \text{ km/h}$.

$A, B$ and $C$ are situated on the bank of a river which is flowing at a constant rate. $B$ is at an equal distance from $A$ and $C$. $A$ swimmer Avinash takes $10 \, h$ to swim from $A$ to $B$ and $B$ to $A$. Also,he takes $8 \, h$ to swim from $A$ to $C$ in downstream. What is the ratio of the speed of Avinash in still water to the speed of the stream?

The speed of a boat in still water is $4 \, km/h$ and the speed of the current is $2 \, km/h$. If the time taken to reach a certain distance upstream is $9 \, hours$,find the time it will take to go the same distance downstream (in $hrs$).

$A$ man can row at a speed of $10 \text{ km/h}$ in still water to a certain upstream point and back to the starting point in a river which flows at $4 \text{ km/h}$. Find his average speed for the total journey (in $\text{km/h}$).