$A$ boat goes $20 \text{ km}$ downstream in $1 \text{ h}$ and the same distance upstream in $2 \text{ h}$. The speed of the boat in still water is ......... $\text{km/h}$.

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?

$A$ 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......$km/h$.

$A$ boat travels upstream from $B$ to $A$ and downstream from $A$ to $B$ in $3$ $hours$. If the speed of the boat in still water is $9\, km/h$ and the speed of the current is $3\, km/h$, find the distance between $A$ and $B$ in kilometres.

Speed of a man is $12 \text{ km/h}$ in still water. If the rate of current is $4 \text{ km/h}$,then the effective speed of the man upstream is ......... $\text{km/h}$.

$A$ man can row $6\, km/h$ in still water. If the river is running at $2\, km/h$,it takes $3\, hours$ more to row upstream than to row downstream for the same distance. How far is the place? (in $km$)