$A$ motor car completes a journey in $10 \, hrs$. It covers the first half of the distance at $21 \, km/hr$ and the second half at $24 \, km/hr$. Find the total distance in $km$.

$A$ train travelling with a speed of $60 \, km/h$ catches another train travelling in the same direction and then leaves it $120 \, m$ behind in $18 \, seconds$. The speed of the second train is (in $km/h$):

Train $A$ crosses a stationary Train $B$ in $50 \,s$ and a pole in $20 \,s$ with the same speed. The length of Train $A$ is $240 \,m$. What is the length of the stationary Train $B$ (in $m$)?

The ratio between the speed of a bike and a train is $15:27$ respectively. Also,a bus covers a distance of $720 \, km$ in $9 \, hours$. The speed of the bike is three-fourths the speed of the bus. How much distance will the train cover in $7 \, hours$? (in $km$)

The jogging track in a sports complex is $726 \, m$ in circumference. Deepak and his wife start from the same point and walk in opposite directions at $4.5 \, km/h$ and $3.75 \, km/h$ respectively. They will meet for the first time in (in $min$):

$A$ man goes from a place $A$ to $B$ at a speed of $12 \, km/h$ and returns from $B$ to $A$ at a speed of $18 \, km/h$. The average speed for the whole journey is? (in $km/h$)