$A$ $150 \, m$ long train takes $10 \, s$ to pass over another $100 \, m$ long train coming from the opposite direction. If the speed of the first train is $30 \, km/h$,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 $minutes$)

$A$ moving train crosses a man standing on a platform and a bridge of $300 \, \text{metres}$ long in $10 \, \text{seconds}$ and $25 \, \text{seconds}$ respectively. What will be the time taken by the train to cross a platform $200 \, \text{metres}$ long? (in $\text{seconds}$)

$A$ train running at $25 \, km/hr$ takes $18 \, seconds$ to pass a platform. Next,it takes $12 \, seconds$ to pass a man walking at $5 \, km/hr$ in the opposite direction. Find the sum of the length of the train and that of the platform (in $m$).

$A$ motorcyclist left $6 \frac{2}{3}$ minutes later than the scheduled time,but in order to reach his destination $21 \, km$ away on time,he had to increase his speed by $12 \, km/h$ from his usual speed. What is the usual speed (in $km/h$) of the motorcyclist?

How many seconds will a $500 \, m$ long train take to cross a man walking with a speed of $3 \, km/h$ in the direction of the moving train, if the speed of the train is $63 \, km/h$?