$A$ and $B$ working separately can do a piece of work in $9$ and $12$ days,respectively. If they work for a day alternatively with $A$ beginning,the work would be completed in (in days):

$A$ worker can complete a piece of work in $50$ days. On the first day,he works alone. On the second day,one more person joins him,on the third day,one more person joins them,and this process continues until the work is completed. How many days are needed to complete the work?

The first man alone can complete a work in $7$ days. The second man alone can do this work in $8$ days. If they work together to complete this work in $3$ days with the help of a boy,and the total payment is $Rs. 1400$,how should the money be divided among them?

$A$ and $B$ can do a piece of work in $10$ days. $B$ and $C$ can do it in $12$ days. $A$ and $C$ can do it in $15$ days. How long will $A$ take to do it alone? (in days)

$P, Q$ and $R$ contract a work for $Rs. 550$. Together,$P$ and $Q$ are supposed to do $\frac{7}{11}$ of the work. How much does $R$ get? (in $Rs.$)

$A$ is twice as good a workman as $B$. Working together,they finish a piece of work in $1.5$ days. $A$ alone can finish the work in (in days):