$A$ alone can do a piece of work in $6$ days and $B$ alone in $8$ days. $A$ and $B$ undertook to do it for $Rs. 3200$. With the help of $C$,they completed the work in $3$ days. How much is to be paid to $C$ (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?

$P, Q$ and $R$ can finish a work in $10, 12$ and $15$ days respectively. If $Q$ stops after $2$ days,how long would it take $P$ and $R$ to finish the remaining work? (in days)

$A$ can do a work in $20 \, days$ and $B$ in $40 \, days$. If they work on it together for $5 \, days$,then the fraction of the work that is left is:

If $3$ men and $4$ boys can earn $Rs. 2100$ in $7$ days,and $11$ men and $13$ boys can earn $Rs. 8300$ in $8$ days,in what time will $7$ men and $9$ boys earn $Rs. 11000$? (in days)

$A$ and $B$,working together,can complete a piece of work in $12$ days. $B$ and $C$ working together can complete the same piece of work in $16$ days. $A$ worked at it for $5$ days and $B$ worked at it for $7$ days. $C$ finished the remaining work in $13$ days. How many days would $C$ alone take to complete it?