$A$ $300 \;m$ long train crosses a platform in $39 \;seconds$,while it crosses a signal pole in $18 \;seconds$. What is the length of the platform? (In $m$)

$A$ train $800 \; m$ long is running at a speed of $78 \; km/hr$. If it crosses a tunnel in $1 \; minute$,then the length (in $m$) of the tunnel is:

$A$ train moves past a telegraph post and a bridge $264 \; m$ long in $8 \; seconds$ and $20 \; seconds$ respectively. What is the speed of the train (in $km/hr$)?

$A$ train covers a distance between two stations $A$ and $B$ in $45$ minutes. If the speed is reduced by $5 \; km/h$,it will cover the same distance in $48$ minutes. What is the distance between the two stations $A$ and $B$ (in $km$)? Also,find the speed of the train.

Two trains, one from Howrah to Patna and the other from Patna to Howrah, start simultaneously. After they meet, the trains reach their destinations after $9 \; \text{hours}$ and $16 \; \text{hours}$ respectively. The ratio of their speeds is

Two trains are moving in opposite directions at $60 \; km/hr$ and $90 \; km/hr$ respectively. Their lengths are $1.1 \; km$ and $0.9 \; km$ respectively. The time taken by the slower train to cross the faster train in seconds is