$A$ man walks a certain distance and rides back in $4 \, h \, 30 \, min$. He could ride both ways in $3 \, h$. The time required by the man to walk both ways is?

In covering a certain distance,the speeds of $A$ and $B$ are in the ratio of $3:4$. $A$ takes $30 \text{ minutes}$ more than $B$ to reach the destination. The time taken by $A$ to reach the destination is (in $\text{hours}$):

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?

Two trains of equal length take $10 \, s$ and $15 \, s$ respectively to cross a telegraph post. If the length of each train is $120 \, m$,in what time (in $s$) will they cross each other while travelling in the same direction?

Three men step off together from the same spot. Their steps measure $63 \, cm$,$70 \, cm$,and $77 \, cm$ respectively. The minimum distance each should cover so that all can cover the distance in complete steps is (in $cm$):

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