$39$ 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?

If $10$ men or $18$ boys can do a work in $15$ days,then the number of days required by $15$ men and $33$ boys to do twice the work is

$A$ and $B$ can complete a piece of work in $15$ days and $10$ days respectively. They contracted to complete the work for $Rs. 30000$. The share of $A$ in the contracted money will be (in $Rs.$)

$7$ 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?

$A$ is thrice as good a workman as $B$ and therefore is able to finish a job in $60\, days$ less than $B.$ Working together,they can do it in (in $days$)

$A$ and $B$ can do a work in $45 \text{ days}$ and $40 \text{ days}$,respectively. They began the work together,but $A$ left after some time and $B$ completed the remaining work in $23 \text{ days}$. After how many days of the start of the work did $A$ leave?