$A$ man moves $20 \, km$ downstream in $5 \, hours$ and $10 \, km$ upstream in the same time. The speed of the stream is...........$km/h$.

$A$ man rows to a place $48 \, km$ away and comes back in $14 \, hours$. He finds that he can row $4 \, km$ with the stream in the same time as $3 \, km$ against the stream. The rate of the stream is:

$A$ 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 $24 \, km$ 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 $...... \, km/hr$.

The ratio of the speed of a motorboat to that of the water current is $36 : 5$. The motorboat travels along with the current in $5 \, h \, 10 \, min$. Find the time taken by the motorboat to return.

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