Some carpenters promised to do a job in $9$ days,but $5$ of them were absent and the remaining men did the job in $12$ days. The original number of carpenters was:

Sixteen men can complete a work in $15$ days,$24$ children can do the same work in $20$ days. In how many days will $8$ men and $8$ children complete the same work?

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

$A$ takes twice as much time as $B$ and $C$ takes thrice as much time as $B$ to finish a piece of work. Working together they can finish the work in $12$ days. The number of days needed for $A$ to do the work alone is:

If $A$ works alone,he would take $4$ days more to complete the job than if both $A$ and $B$ worked together. If $B$ worked alone,he would take $16$ days more to complete the job than if $A$ and $B$ work together. How many days would they take to complete the work if both of them worked together?

$P$ can do $\left(\frac{1}{4}\right)$ of the work in $10$ days. $Q$ can do $40\%$ of the work in $40$ days and $R$ can do $\left(\frac{1}{3}\right)$ of the work in $13$ days. Who will complete the work first?