$A$ speed of $45\, km/h$ is equivalent to which speed in $m/s$?

$A$ train is running at a uniform speed of $60 \, km/h$. It passes a railway platform in $15 \, s$. If the length of the platform is $130 \, m$,then the length of the train is (in $m$):

Two men $A$ and $B$ walk from $P$ to $Q$ at a distance of $21 \text{ km}$ at speeds of $3 \text{ km/h}$ and $4 \text{ km/h}$ respectively. $B$ reaches $Q$ and returns immediately and meets $A$ at $R$. The distance from $P$ to $R$ is (in $\text{km}$):

$A$ car covers the first $39 \, km$ of its journey in $45 \, minutes$ and the remaining $25 \, km$ in $35 \, minutes.$ What is the average speed of the car (in $km/h$)?

Two trains start from $P$ and $Q$ respectively and travel towards each other at a speed of $50\, km/hr$ and $40\, km/hr$ respectively. By the time they meet,the first train has travelled $100\, km$ more than the second. The distance between $P$ and $Q$ is (in $km$):

$A$ man starts from his home and walks $10 \, km$ towards South. Then he turns right and walks $6 \, km$,again he turns right and goes $10 \, km$. Finally,he turns right and walks $5 \, km$. At what distance is he from his starting point? (in $km$)