$A$ train,when moving at an average speed of $40 \, km/hr$,reaches its destination on time. When its average speed becomes $35 \, km/hr$,it reaches its destination $15 \, minutes$ late. Find the length of the journey in $km$.

$A$ student walks from his house at a speed of $2 \, km/h$ and reaches his school $6 \, minutes$ late. The next day,he increases his speed by $1 \, km/h$ and reaches $6 \, minutes$ before school time. How far is the school from his house? (in $km$)

How many $km/h$ does a man walk who passes through a street $600 \, m$ long in $5 \, minutes$?

$A$ car moving in the same direction passes a man walking at $4\, km/h$. The man can see the car for $3\, minutes$ and the visibility is up to a distance of $130\, m$. The speed of the car is: (in $km/h$)

$A$ boy walking at a speed of $10\, km/hr$ reaches his school $15\, minutes$ late. Next time he increases his speed by $2\, km/hr$, but still he is late by $5\, minutes$. Find the distance of his school from his house (in $km$).

The average speed of a car is $1 \frac{4}{5}$ times the average speed of a bus. $A$ tractor covers $575 \, km$ in $23 \, hours$. How much distance will the car cover in $4 \, hours$ if the speed of the bus is twice the speed of the tractor? (in $km$)