$A$ walks around a circular field at the rate of one $round/hour$,while $B$ runs around it at the rate of six $rounds/hour$. They start in the same direction from the same point at $7.30 \, a.m$. They shall first cross each other at (in $a.m.$)

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?

The call rate of a $SIM$ of Company $A$ is one paisa for every three seconds. Another $SIM$ of Company $B$ charges $45 \text{ paisa per minute}$. $A$ man talked for $591 \text{ seconds}$ from the $SIM$ of Company $A$ and $780 \text{ seconds}$ from the $SIM$ of Company $B$. What would be the total amount he spent? (in $Rs.$)

$A$ train $160 \ m$ long passes a standing man in $18 \ s$. The speed of the train is (in $km/h$):

$A$ $280 \, m$ long train moving with an average speed of $108 \, km/h$ crosses a platform in $12 \, s$. $A$ man crosses the same platform in $10 \, s$. What is the speed of the man in $m/s$?

$A$ person has to reach a certain place at a certain time. He finds that he will be $15 \text{ minutes}$ late if he walks at $4 \text{ km/h}$,and $10 \text{ minutes}$ earlier if he walks at $6 \text{ km/h}$. How far has he to walk? (in $\text{km}$)