$A$ 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 $hours$)

Ramesh sees a train passing over a $1 \, km$ long bridge. The length of the train is half that of the bridge. If the train passes the bridge in $2 \, minutes$,the speed of the train is (in $km/h$)

Two cars $P$ and $Q$ start at the same time from $A$ and $B$ which are $120 \, km$ apart. If the two cars travel in opposite directions,they meet after $1 \, hour$,and if they travel in the same direction (from $A$ towards $B$),then $P$ meets $Q$ after $6 \, hours$. What is the speed of car $P$ (in $km/hr$)?

$A$ person covers half of his journey at $30 \text{ km/h}$ and the remaining half at $20 \text{ km/h}$. The average speed for the whole journey is (in $\text{km/h}$)

$A$ train,when moving at an average speed of $40 \, km/hr$,reaches its destination on time. When its average speed becomes $35 \, km/hr$,it reaches its destination $15 \, minutes$ late. Find the length of the journey in $km$.

Walking $\frac{6}{7}$ of his usual speed, a man is $12 \, \text{minutes}$ late. The usual time taken by him to cover that distance is