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

$A$ 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 $12 \text{ days}$?

$A$ can do a work in $15\, days$ and $B$ in $20\, days.$ If they work on it together for $4\, days,$ then the fraction of the work that is left is

$10$ men can finish a piece of work in $10$ days,whereas it takes $12$ women to finish it in $10$ days. If $15$ men and $6$ women undertake to complete the work,how many days will they take to complete it?

Working $7\, \text{hours}$ daily,$24$ men can complete a piece of work in $27$ $\text{days}$. In how many $\text{days}$ would $14$ men complete the same piece of work working $9\, \text{hours}$ daily?

$7$ 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?