$A$ and $B$ can together finish a work in $30$ days. They worked together for $20$ days and then $B$ left. After another $20$ days,$A$ finished the remaining work. In how many days can $A$ alone finish the job?

$P$ is twice as good a workman as $Q,$ and together they finish a work in $16$ days. In how many days can it be done by each separately?

$3$ women and $18$ children together take $2$ days to complete a piece of work. How many days will $9$ children alone take to complete the piece of work,if $6$ women alone can complete the piece of work in $3$ days?

$A,$ $B,$ and $C$ have to type $506$ pages to finish an assignment. $A$ can type a page in $12$ minutes,$B$ in $15$ minutes,and $C$ in $24$ minutes. If they divide the task into three parts so that all three of them spend an equal amount of time typing,what is the number of pages that $B$ should type?

$P, Q$ and $R$ can do a piece of work in $60$ days,$100$ days and $80$ days respectively. They work together to finish the work and receive $Rs. 2256$. Then $P$ will get (in $Rs.$)

$A$ does $\frac{2}{5}$ of a work in $9$ days. Then $B$ joined him and they together completed the remaining work in $6$ days. $B$ alone can finish the whole work in (in days):