$A$ and $B$ are $20 \text{ km}$ apart. $A$ can walk at an average speed of $4 \text{ km/hr}$ and $B$ at $6 \text{ km/hr}$. If they start walking towards each other at $7 \text{ a.m.}$,when will they meet? (in $\text{a.m.}$)

The distance between places $A$ and $B$ is $999 \, km$. An express train leaves place $A$ at $6 \, am$ and runs at a speed of $55.5 \, km/h$. The train stops on the way for $1 \, hr \, 20 \, min$. It reaches $B$ at?

Two trains,each of length $125 \, m$,are running on parallel tracks in opposite directions. One train is running at a speed of $65 \, km/h$ and they cross each other in $6 \, s$. The speed of the other train is (in $km/h$):

Aditya covered a certain distance at some speed. Had he moved $3 \text{ km/h}$ faster, he would have taken $40 \text{ minutes}$ less. If he had moved $2 \text{ km/h}$ slower, he would have taken $40 \text{ minutes}$ more. The distance is: (in $\text{ km}$)

If a train runs at $40 \text{ km/h}$,it reaches its destination late by $11 \text{ minutes}$. But if it runs at $50 \text{ km/h}$,it is late by $5 \text{ minutes}$ only. The correct time (in $\text{minutes}$) for the train to complete the journey is

$A$ person goes from point $A$ to $B$ with a speed of $55 \text{ km/hr}$ and returns with a speed of $65 \text{ km/hr}$. What is the average speed (in $\text{km/hr}$) of the person while going and coming back from $A$ to $B$?