The ratio of the speeds of a car,a train,and a bus is $5:9:4$. The average speed of the car,the bus,and the train together is $72 \text{ km/h}$. What is the average speed of the car and the train together? (in $\text{km/h}$)

$A$ train,$240 \, m$ long,crosses a man walking along the line in the opposite direction at the rate of $3 \, km/h$ in $10 \, seconds$. The speed of the train is (in $km/h$):

$A$ train running at the speed of $66 \, km/h$ crosses a signal pole in $18 \, seconds$. What is the length of the train (in $m$)?

Two trains,Kanpur Mail and Delhi Mail,start at the same time from stations Kanpur and Delhi respectively towards each other. After passing each other,they take $12\, \text{hours}$ and $3\, \text{hours}$ to reach Delhi and Kanpur respectively. If the Kanpur Mail is moving at the speed of $48\, \text{km/hr}$,the speed of the Delhi Mail is (in $\text{km/hr}$):

Two trains are moving in the same direction at $50 \, km/h$ and $30 \, km/h$. The faster train crosses a man in the slower train in $18 \, seconds$. Find the length of the faster train (in $m$).

By walking at $\frac{3}{4}$ of his usual speed,a man reaches his office $20 \text{ minutes}$ later than usual. His usual time is (in $\text{minutes}$):