$A$ farmer can plough a field working $6 \text{ hours per day}$ in $18 \text{ days}$. How many $\text{hours per day}$ must the farmer work to finish the same work in $12 \text{ days}$?

$A$ certain job was assigned to a group of men to do in $20$ days. But,$12$ men did not turn up for the job and the remaining men did the job in $32$ days. The original number of men in the group was:

Nikita,Nishita,and Kavita can complete a work in $2 \frac{2}{3}$ days. If Nishita and Kavita can complete it in $4$ days,and Nishita alone can do it in $6$ days,then in how many days can Nikita and Nishita complete the work?

$A$ 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 $days$)

If $12$ men or $18$ women can build a wall in $14$ days,then working at the same rate,$8$ men and $16$ women can build the same wall in how many days?

$7$ men can complete a piece of work in $12$ days. How many additional men will be required to complete double the work in $8$ days?