If a distance of $50\, m$ is covered in $1\, minute$,$90\, m$ in $2\, minutes$,and $130\, m$ in $3\, minutes$,find the total distance covered in $15\, minutes$ (in $m$).

Two places $A$ and $B$ are $100 \, km$ apart on a highway. One car starts from $A$ and another from $B$ at the same time. If the cars travel in the same direction at a constant speed,they meet in $5 \, hours$. If the cars travel towards each other,they meet in $1 \, hour$. What is the speed of the car running faster? (in $km/h$)

Two boys jointly begin to write a booklet containing $817$ lines. The first boy starts with the first line and writes $200$ lines an hour. The second boy starts with the last line,then writes line $816$ and so on,proceeding backwards at the rate of $150$ lines an hour. They will meet on:

$A$ man can reach a certain place in $30 \, h$. If he reduces his speed by $\frac{1}{15}^{th}$,he goes $10 \, km$ less in that same time. Find his speed in $km/h$.

$A$ train travelling at a speed of $55\, km/hr$ travels from place $X$ to place $Y$ in $4\, hours$. If its speed is increased by $5\, km/hr$,then the time of journey is reduced by (in $minutes$):

$A$ $180\, m$ long train crosses another $270\, m$ long train running in the opposite direction in $10.8\, seconds$. If the speed of the first train is $60\, km/h$, what is the speed of the second train in $km/h$?