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 complete a piece of work in $40$ days. He starts working,but having some other engagements,he leaves after $5$ days. Thereafter,$B$ completes the remaining work in $21$ days. How many days would $A$ and $B$ take to complete this work working together?

$A$ can do a piece of work in $14$ days,which $B$ can do in $21$ days. They begin together,but $3$ days before the completion of the work,$A$ leaves. The total number of days to complete the work is:

Two men undertake a piece of work for $Rs. 600$. Individually,they can complete the work in $6$ days and $8$ days,respectively. With the assistance of a boy,they completed the work in $3$ days. The boy's share should be (in $Rs.$)

$A$ and $B$ can do a piece of work in $30$ and $36$ days respectively. They began the work together,but $A$ leaves after some days and $B$ finished the remaining work in $25$ days. After how many days did $A$ leave?

$P$ can complete $\frac{1}{4}$ of a work in $10$ days,$Q$ can complete $40\%$ of the same work in $15$ days,$R$ can complete $\frac{1}{3}$ of the work in $13$ days,and $S$ can complete $\frac{1}{6}$ of the work in $7$ days. Who will be able to complete the work first?