$A$ boat covers a certain distance downstream in $1 \text{ hour}$,while it comes back in $1.5 \text{ hours}$. If the speed of the stream is $3 \text{ km/hr}$,what is the speed of the boat in still water? (in $\text{km/hr}$)

$A$ man can row $30 \text{ km}$ upstream and $44 \text{ km}$ downstream in $10 \text{ hours}$. Also,he can row $40 \text{ km}$ upstream and $55 \text{ km}$ downstream in $13 \text{ hours}$. Find the rate of the current and the speed of the man in still water.

$A$ man can row $30 \text{ km}$ downstream and return in a total of $8 \text{ h}$. If the speed of the boat in still water is $4$ times the speed of the current,then the speed of the current is ....... $\text{km/h}$.

$A$ person can row a certain distance downstream in $6$ $hours$ and return the same distance in $9$ $hours.$ If the stream flows at the rate of $2 \frac{1}{4} \text{ km/h},$ find how far he can row in an hour in still water (in $\text{km/h}$).

$A$ man can row $20 \text{ km/h}$ in still water and the speed of the stream is $5 \text{ m/s}$. The ratio of the speed of the man to the speed of the current is:

Rahul can travel $12 \text{ miles}$ downstream in a certain river in $6 \text{ hours}$ less than it takes him to travel the same distance upstream. But if he could double his usual rowing rate for his $24 \text{ mile}$ round trip,the downstream $12 \text{ miles}$ would take only one hour less than the upstream $12 \text{ miles}$. What is the speed of the current in $\text{miles/hour}$?