$A$ train completes a non-stop journey in $8 \, \text{hours}$. If it had travelled $5 \, \text{km/h}$ faster, it would have completed the journey in $6 \, \text{hours} \, 40 \, \text{minutes}$. What is its lowest speed in $\text{km/h}$?

What is the speed of the train in $km/h$?
Statements:
$I.$ The train crosses an $x$ meter-long platform in $n$ seconds.
$II.$ The length of the train is $y$ meters.
$III.$ The train crosses a signal pole in $m$ seconds.

In covering a certain distance,the speeds of $A$ and $B$ are in the ratio of $3:4$. $A$ takes $30 \text{ minutes}$ more than $B$ to reach the destination. The time taken by $A$ to reach the destination is (in $\text{hours}$):

$A$ car travels the first one-third of a certain distance with a speed of $10\, km/hr$,the next one-third distance with a speed of $20\, km/hr$,and the last one-third distance with a speed of $60\, km/hr$. The average speed of the car for the whole journey is (in $km/hr$):

If a person walks at $14 \, km/hr$ instead of $10 \, km/hr$,he would have walked $20 \, km$ more. The actual distance travelled by him is (in $km$)

$A$ man covers a certain distance by car driving at $70 \, km/hr$ and he returns to the starting point riding on a scooter at $55 \, km/hr$. Find his average speed for the whole journey in $km/hr$.