$A$ man walks at the rate of $5 \, km/hr$ for $6 \, hours$ and at $4 \, km/hr$ for $12 \, hours$. The average speed of the man (in $km/hr$) is:

$A$ man with $\frac{3}{5}$ of his usual speed reaches the destination $2 \frac{1}{2}$ hours late. Find his usual time to reach the destination? (in $hours$)

Two trains,$130 \,m$ and $110 \,m$ long,are moving in the same direction. The faster train takes $1 \,minute$ to pass the other completely. If they are moving in opposite directions,they pass each other completely in $3 \,seconds$. Find the speed of each train (in $m/s$).

$50$ trees are standing in a line such that the distance between any two consecutive trees is the same. $A$ car takes $18 \, seconds$ to travel from the $13^{th}$ tree to the $34^{th}$ tree. How much time (in $seconds$) will it take to reach from the first tree to the $50^{th}$ tree?

$A$ bus travels $720 \text{ km}$ in $20 \text{ hours}$. Calculate its average speed in $\text{metres/seconds}$.

$A$ $570 \, m$ long train crosses a platform of equal length in $15 \, s$. What is the speed of the train in $m/s$?