Sunil completes a work in $4$ days,whereas Dinesh completes the work in $6$ days. Ramesh works $1 \frac{1}{2}$ times as fast as Sunil. The three together can complete the work in (in days):

$A$ can lay railway track between two given stations in $16 \, days$ and $B$ can do the same job in $12 \, days$. With the help of $C$,they did the job in $4 \, days$ only. Then $C$ alone can do the job in (in $days$)

$A, B$ and $C$ together can finish a piece of work in $4$ days. $A$ alone can do it in $12$ days and $B$ alone in $18$ days. How many days will be taken by $C$ to do it alone?

$A$ can do a piece of work in $20 \, \text{days}$ and $B$ in $30 \, \text{days}$. They work together for $7 \, \text{days}$ and then, both leave the work. Then, $C$ alone finishes the remaining work in $10 \, \text{days}$. In how many $\text{days}$ will $C$ finish the full work?

$20$ men can complete a piece of work in $16$ days. After $5$ days from the start of the work,some men left. If the remaining work was completed by the remaining men in $18 \frac{1}{3}$ days,how many men left after $5$ days from the start of the work?

$A$ contractor has the target of completing a work in $40 \text{ days}$. He employed $20$ persons who completed $\frac{1}{4}$ of the work in $10 \text{ days}$ and left. The number of additional persons he has to employ to finish the remaining part of the work as per the target is: