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 speed of a boat in still water is $6\, km/hr$ and the speed of the stream is $1.5\, km/hr$. $A$ man rows to a place at a distance of $22.5\, km$ and comes back to the starting point. The total time taken by him is

$A$ man swimming in a stream which flows at $1 \frac{1}{2} \text{ km/h}$ finds that in a given time he can swim twice as far with the stream as he can against it. At what rate does he swim? (in $\text{km/h}$)

$A$ boat goes $13\, km$ upstream in $39\, minutes$. The speed of the stream is $3\, km/h$. The speed of the boat in still water is......$km/h$.

In a river flowing at $2\, km/h$, a boat travels $32\, km$ upstream and then returns downstream to the starting point. If its speed in still water is $6\, km/h$, find the total journey time in hours.

$A$ man can row $15\, km$ downstream in $3\, hours$ and $5\, km$ upstream in $2.5\, hours$. His speed in still water in $(km/hr)$ is: