$A$ person has to reach a certain place at a certain time. He finds that he will be $15 \text{ minutes}$ late if he walks at $4 \text{ km/h}$,and $10 \text{ minutes}$ earlier if he walks at $6 \text{ km/h}$. How far has he to walk? (in $\text{km}$)

$A$ $180 \, m$ long train crosses another $270 \, m$ long train running from the opposite direction in $10.8 \, s$. If the speed of the first train is $60 \, km/h$,what is the speed of the second train in $km/h$?

$A$ train starts from station $A$ at $9\, am$ and travels at $50\, km/h$ towards station $B,$ which is $210\, km$ away. Another train starts from station $B$ at $11\, am$ and travels at $60\, km/h$ towards station $A.$ At what distance from station $A$ will they meet? (in $km$)

When Alisha goes by car at $50 \, km/h$,she reaches her office $5 \, minutes$ late. But when she takes her motorbike,she reaches $3 \, minutes$ early. If her office is $25 \, km$ away,what is the approximate average speed at which she rides her motorbike? (in $km/h$)

Two trains of equal length are running on parallel tracks in the same direction at the speeds of $46 \, km/h$ and $36 \, km/h$. The faster train passes the slower train in $36 \, seconds$. The length of each train is (in $m$):

Two cyclists started simultaneously towards each other and meet each other $3$ hours $20$ minutes later. How much time will it take the slower cyclist to cover the whole distance if the first arrived at the place of departure of the second $5$ hours later than the second arrived at the point of departure of the first? (in hours)