$A$ train running at a speed of $40 \, m/s$ crosses a pole in $21 \, s$ less than the time it requires to cross a bridge $3.5$ times its length at the same speed. What is the length of the bridge (in $m$)?

$A$ train covers a distance between station $A$ and station $B$ in $45 \, min$. If the speed of the train is reduced by $5 \, km/h$,then the same distance is covered in $48 \, min$. The distance between stations $A$ and $B$ is? (in $km$)

$A$ $280 \, m$ 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 $m/s$?

Two trains start at the same time from two stations and proceed towards each other at the speeds of $20 \, km/h$ and $25 \, km/h$ respectively. When they meet,it is found that one train has travelled $80 \, km$ more than the other. Find the distance between the two stations (in $km$).

In a race of $1 \, km$,$A$ gives $B$ a start of $100 \, m$ and still wins by $20 \, s$. But if $A$ gives $B$ a start of $25 \, s$,$B$ wins by $50 \, m$. The time taken by $A$ to run $1 \, km$ is (in $s$):

$A$ train of length $100\, m$ crosses another train of length $150\, m,$ running on a parallel track in the opposite direction in $9\, s.$ If the speed of the train having length $150\, m$ is $40\, km/h,$ what is the speed (in $km/h$) of the other train?