Speed of a man is $10 \text{ km/h}$ in still water. If the rate of current is $3 \text{ km/h}$,then the effective speed of the man upstream is ....... $\text{km/h}$.

Rohit can row a certain distance downstream in $8$ $hours$ and return the same distance in $12$ $hours$. If the stream flows at the rate of $5$ $km/hr$,find the speed of Rohit in still water (in $km/hr$).

$A$ boat covers a certain distance downstream in $2$ $hours$,but takes $4$ $hours$ to return upstream to the starting point. If the speed of the stream is $3$ $km/h$,find the speed of the boat in still water (in $km/h$).

$A$ river is flowing with a steady speed of $4\, km/h$. One rows his boat downstream in the river and then returns by rowing upstream in the same river. When he returns to the starting point,the total distance covered by him is $42\, km$. If the return journey takes $2\, h$ more than his outward journey,then the speed of his rowing in still water must be (in $km/h$)

$A$ swimmer covers a distance of $28\, km$ against the current and $40\, km$ in the direction of the current. If in each case he takes $4\, hours$,then the speed of the current is..........$km/h$.

$A$ boat covers $12\, km$ upstream and $18\, km$ downstream in $3\, hours,$ while it covers $36\, km$ upstream and $24\, km$ downstream in $6\frac{1}{2}\, hours.$ What is the speed of the current? (in $km/h$)