$A$ man's speed with the current is $15 \, km/hr$,and the speed of the current is $2.5 \, km/hr$. The man's speed against the current is.......$km/hr$

$A$ 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 (in $\text{km/h}$).

The speed of a boat in still water is $6\, km/h$ and the speed of the stream is $1.5\, km/h$. $A$ man rows to a place at a distance of $22.5\, km$ and comes back to the starting point. Find the total time taken by him (in $hours$).

$A$ boat travels $18 \, km$ upstream in $6 \, hours$. How long (in $hours$) will it take to cover the same distance downstream if the speed of the current is one-fourth the speed of the boat in still water?

Speed of a motorboat in still water is $45\, km/h$. If the motorboat travels $80\, km$ along the stream in $1\, h\, 20\, min$,then the time taken by it to cover the same distance against the stream will be:

$A$ boat running upstream takes $8$ $hours$ $48$ $minutes$ to cover a certain distance,while it takes $4$ $hours$ to cover the same distance running downstream. What is the ratio between the speed of the boat and speed of the current respectively?