$A$ man can row at a speed of $4.5 \text{ km/hr}$ in still water to a certain upstream point and back to the starting point in a river which flows at $1.5 \text{ km/hr}$. Find his average speed for the total journey in $\text{km/hr}$.

Speeds of a boat along the current and against the current are $10 \ km/hr$ and $8 \ km/hr$ respectively. What is the speed (in $km/hr$) of the current?

If a man's rate with the current is $12 \text{ km/h}$ and the rate of the current is $1 \frac{1}{2} \text{ km/h}$,then his rate against the current is ...... $\text{km/h}$.

The current of a stream runs at the rate of $4 \text{ km/h}$. $A$ boat goes $6 \text{ km}$ and comes back to the starting point in $2 \text{ hours}$. The speed of the boat in still water is ....... $\text{km/h}$.

$A$ man can row a boat at a speed of $8\, km/h$ in still water. He was rowing the boat downstream from one point to another. After travelling half of the distance,the motor of the boat failed. He continued to drift along the stream and reached his destination,taking $6\, hours$ more than the usual time. The speed of the stream is $2\, km/h$. What is the total distance between the two points in $km$?

$A$ boat takes $90$ minutes less to travel $36$ miles downstream than to travel the same distance upstream. If the speed of the boat in still water is $10$ miles/hour,the speed of the stream is.......miles/hour.