$A$ $100\, m$ long train completely passes a man walking in the same direction at $6\, km/h$ in $5\, s$ and also a car travelling in the same direction in $6\, s$. At what speed was the car travelling? (in $km/h$)

Mohan covers $10.2 \, km$ in $3 \, hours$. The distance covered by him in $5 \, hours$ is (in $km$):

Three men step off together from the same spot. Their steps measure $63 \, cm$,$70 \, cm$,and $77 \, cm$ respectively. The minimum distance each should cover so that all can cover the distance in complete steps is (in $cm$):

$A$ and $B$ are two stations. $A$ train goes from $A$ to $B$ at $64 \text{ km/h}$ and returns to $A$ at a slower speed. If its average speed for the whole journey is $56 \text{ km/h}$,at what speed did it return? (in $\text{km/h}$)

Heena and Renu are competing in a $100\, m$ race. Initially,Heena runs at twice the speed of Renu for the first $50\, m$. After the $50\, m$ mark,Heena runs at $\frac{1}{4}$ of her initial speed,while Renu continues to run at her original speed. If Renu catches up with Heena at a distance of $N$ meters from the finish line,then $N$ is equal to (in meters).

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 $km/h$)