$A$ man with $\frac{3}{5}$ of his usual speed reaches the destination $2 \frac{1}{2}$ hours late. Find his usual time to reach the destination? (in $hours$)

$A$ $75 \, m$ long train is moving at $20 \, km/h$. It will cross a man standing on the platform in (in $sec$):

$A$ boy rides his bicycle $10 \, km$ at an average speed of $12 \, km/hr$ and again travels $12 \, km$ at an average speed of $10 \, km/hr$. His average speed for the entire trip is approximately (in $km/hr$)

The distance between places $A$ and $B$ is $999 \, km$. An express train leaves place $A$ at $6 \, am$ and runs at a speed of $55.5 \, km/h$. The train stops on the way for $1 \, hr \, 20 \, min$. It reaches $B$ at?

$A$ passenger train running at the speed of $80 \text{ km/h}$ leaves the railway station $6 \text{ hours}$ after a goods train leaves and overtakes it in $4 \text{ hours}$. What is the speed of the goods train? (in $\text{km/h}$)

The speed of a car increases by $2\, km/h$ after every hour. If the distance travelled in the first hour was $35\, km$,what is the total distance travelled in $12$ hours? (in $km$)