$A$ train is moving with a speed of $180 \, km/hr$. Its speed in $m/s$ is:

Two stations $A$ and $B$ are $100 \, km$ apart on a straight line. One train starts from $A$ at $7 \, am$ and travels towards $B$ at $20 \, km/h$ speed. Another train starts from $B$ at $8 \, am$ and travels towards $A$ at $25 \, km/h$ speed. At what time will they meet?

$A$ car covers the first $39 \, km$ of its journey in $45 \, minutes$ and the remaining $25 \, km$ in $35 \, minutes$. What is the average speed of the car in $km/h$?

$A$ person travels from $P$ to $Q$ at a speed of $40 \, km/h$ and returns from $Q$ to $P$ by increasing his speed by $50\%$. What is his average speed for the entire journey? (in $km/h$)

Two men start together to walk a certain distance,one at $4 \, km/h$ and another at $3 \, km/h$. The former arrives half an hour before the latter. Find out the distance in $km$.

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 $m$)?