Walking at three-fourth of his usual speed, a man covers a certain distance in $2 \, \text{hours}$ more than the time he takes to cover the distance at his usual speed. The time taken by him to cover the distance with his usual speed is (in $\text{hours}$):

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

Two men $A$ and $B$ start from a place $P$ walking at $3 \, km/h$ and $3.5 \, km/h$ respectively. How many $km$ will they be apart at the end of $3 \, h$,if they walk in opposite directions (in $.5$)?

The distance between two stations,Delhi and Amritsar,is $450 \, km$. $A$ train starts at $4 \, p.m.$ from Delhi and moves towards Amritsar at an average speed of $60 \, km/hr$. Another train starts from Amritsar at $3:20 \, p.m.$ and moves towards Delhi at an average speed of $80 \, km/hr$. At what time will the two trains meet?

What is the length of the bridge (in $m$) that a man riding at $15 \, km/h$ can cross in $5 \, minutes$?

$A$ train is running at a uniform speed of $60 \, km/h$. It passes a railway platform in $15 \, s$. If the length of the platform is $130 \, m$,then the length of the train is (in $m$):