$A$ train leaves the station $1 \, hr$ before the scheduled time. The driver decreases its speed by $4 \, km/hr$. At the next station $120 \, km$ away,the train reaches on time. Find the original speed of the train in $km/hr$.

The distance between places $A$ and $B$ is $999 \text{ km}$. An express train leaves place $A$ at $6:00 \text{ am}$ and runs at a speed of $55.5 \text{ km/h}$. The train stops on the way for $1 \text{ hour } 20 \text{ minutes}$. At what time does it reach place $B$ (in $\text{pm}$)?

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 $\text{hours}$):

$A$ $180\, m$ long train crosses another $270\, m$ long train running in the opposite direction in $10.8\, seconds$. If the speed of the first train is $60\, km/h$, what is the speed of the second train in $km/h$?

$A$ car moving in the same direction passes a man walking at $4\, km/h$. The man can see the car for $3\, minutes$ and the visibility is up to a distance of $130\, m$. The speed of the car is: (in $km/h$)

$A$ train leaves a station $A$ at $7:00 \text{ am}$ and reaches another station $B$ at $11:00 \text{ am}.$ Another train leaves station $B$ at $8:00 \text{ am}$ and reaches $A$ at $11:30 \text{ am}.$ At what time do the two trains cross each other?