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

$A$ boat goes $24 \, km$ upstream and $28 \, km$ downstream in $6 \, hours$. It goes $30 \, km$ upstream and $21 \, km$ downstream in $6 \, hours$ and $30 \, minutes$. The speed of the boat in still water is $...... \, km/hr$.

$A$ man can row $7 \frac{1}{2} \, km/hr$ in still water. If in a river running at $1.5 \, km/hr$,it takes him $50 \, minutes$ to row to a place and back,how far off is the place? (in $km$)

$A$ boat goes $40\, km$ upstream in $8\, h$ and $36\, km$ downstream in $6\, h$. The speed of the boat in still water is......$km/h$

$A$ 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 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 $3\, km/h$,the distance between $A$ and $B$ is........$km$.