$A$ man swimming in a stream which flows at $1.5 \, km/hr$ 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 still water? (in $km/hr$)

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 ...... $\text{km/h}$.

$A$ 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 $km/h$.

$A$ 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 $km$)

In a stream running at $2 \ km/h$,a motorboat goes $6 \ km$ upstream and back again to the starting point in $33 \ minutes$. Find the speed of the motorboat in still water. (in $km/h$)

Twice the speed downstream is equal to thrice the speed upstream. The ratio of the speed in still water to the speed of the current is: