Working efficiencies of $A$ and $B$ for completing a piece of work are in the ratio $3: 4$. The number of days taken by them to complete the work will be in the ratio:

$A$ can finish a work in $24$ days,$B$ in $9$ days and $C$ in $12$ days. $B$ and $C$ start the work but are forced to leave after $3$ days. The remaining work was done by $A$ in (in days):

If $3$ men or $5$ women can reap a field in $43$ days,how long will $5$ men and $6$ women take to reap it? (in days)

$39$ persons can repair a road in $12$ days working $5$ hours per day. In how many days will $30$ persons working $6$ hours per day complete the same work?

$A, B$ and $C$ can do a piece of work individually in $8, 10$ and $15$ days respectively. $A$ and $B$ start working,but $A$ quits after working for $2$ days. After this,$C$ joins $B$ until the completion of the work. In how many days will the work be completed?

$10$ men working $6\, \text{h}$ a day can complete a work in $18\, \text{days}$. How many $\text{hours per day}$ must $15$ men work to complete the same work in $12\, \text{days}$?