$A$ car travels the first $39 \, km$ distance in $45 \, minutes$ and the next $25 \, km$ distance in $35 \, minutes$. What is its average speed in $km/h$?

$A$ train travelling with a speed of $60 \, km/h$ catches another train travelling in the same direction and then leaves it $120 \, m$ behind in $18 \, seconds$. The speed of the second train is (in $km/h$):

$A$ man is walking at a speed of $10 \, km/h$. After every $1 \, km$, he takes a rest for $5 \, minutes$. How much time will he take to cover a distance of $5 \, km$? (in $minutes$)

Two buses start at the same time from two bus stations and proceed towards each other at the rates of $20 \, km/h$ and $25 \, km/h$ respectively. When they meet,one bus has travelled $80 \, km$ more than the other. Find the distance between the two bus stations (in $km$).

$A$ boy is running at a speed of $p \, km/h$ to cover a distance of $1 \, km$. However,due to the slippery ground,his speed is reduced by $q \, km/h$ $(p > q)$. If he takes $r$ hours to cover the distance,then:

Two trains start at the same time from two stations and proceed towards each other at the speeds of $20 \, km/h$ and $25 \, km/h$ respectively. When they meet,it is found that one train has travelled $80 \, km$ more than the other. Find the distance between the two stations (in $km$).