If a man's rate with the current is $12\, km/h$ and the rate of current is $1.5\, km/h$,then the man's rate against the current in $km/h$ is...........

What time will be taken by a boat to cover a distance of $128\, km$ along the stream,if the speed of a boat in still water is $24\, km/h$ and the speed of the stream is $8\, km/h$? (in $h$)

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:

There is a road beside a river. Two friends started from a place $A,$ moved to a temple situated at another place $B$ and then returned to $A$ again. One of them moves on a cycle at a speed of $12\, km/hr,$ while the other sails on a boat at a speed of $10\, km/hr.$ If the river flows at the speed of $4\, km/hr,$ which of the two friends will return to place $A$ first?

$A$ man can row against the current $3/4$ of a kilometre in $15$ $min$ and returns the same distance in $10$ $min.$ The ratio of his speed to that of the current is:

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