$A$ is twice as good a workman as $B$ and together they finish a piece of work in $14$ days. The number of days taken by $A$ alone to finish the work is (in days):

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 complete a work in $15$ days and $10$ days respectively. They started doing the work together,but after $2$ days $B$ had to leave and $A$ alone completed the remaining work. In how many days was the whole work completed?

$A$ team of $30$ men is supposed to do a work in $38$ days. After $25$ days,$5$ more men were employed and the work was finished one day earlier. How many days would it have been delayed if $5$ more men were not employed? (in days)

$A$ certain number of persons can complete a piece of work in $55 \text{ days}$. If there were $6$ persons more,the work could be finished in $11 \text{ days}$ less. How many persons were originally there?

$P, Q$ and $R$ undertake to do a work for $Rs. 707$. $P$ and $Q$ together do $\frac{5}{7}$ of the work and the rest is done by $R$ alone. How much should $R$ get? (in $Rs.$)