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

Two trains are running at a speed of $40 \, km/h$ and $20 \, km/h$ respectively in the same direction. The fast train completely passes a man sitting in the slow train in $5 \, seconds$. The length of the fast train is (in $m$):

$A$ train speeds past a pole in $15 \, \text{seconds}$ and speeds past a $100 \, \text{meters}$ long platform in $25 \, \text{seconds}$. Its length in meters is:

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

Car $A$ runs at the speed of $65 \text{ km/h}$ and reaches its destination in $8 \text{ hours}$. Car $B$ runs at the speed of $70 \text{ km/h}$ and reaches its destination in $4 \text{ hours}$. What is the respective ratio of distances covered by Car $A$ and Car $B$?

$A$ man performs $\frac{2}{15}$ of the total journey by rail,$\frac{9}{20}$ by tonga,and the remaining $10 \ km$ on foot. The total journey is (in $km$):