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

Some staff promised to do a job in $18 \, days,$ but $6$ of them went on leave. So,the remaining men took $20 \, days$ to complete the job. How many men were there originally?

How many men will be required to plough $100 \, acres$ of land in $10 \, days$ if $10 \, men$ require $8 \, days$ to plough $20 \, acres$ of land?

$A$ can do a certain work in the same time in which $B$ and $C$ together can do it. If $A$ and $B$ together could do it in $10$ days and $C$ alone in $50$ days,then $B$ alone could do the work in (in days)

$A$ and $B$ together can do a piece of work in $10$ days. $A$ alone can do it in $30$ days. The time in which $B$ alone can do it is (in days):

$3$ persons undertake to complete a piece of work for $Rs. 1,200$. The $first$ person can complete the work in $8$ days,the $second$ person in $12$ days,and the $third$ person in $16$ days. They complete the work with the help of a $fourth$ person in $3$ days. What does the $fourth$ person get? (in $Rs.$)