$P$,$Q$ and $R$ contracted to do a work for $Rs. 4200$. $P$ can do the work in $6$ days,$Q$ in $10$ days and $R$ in $12$ days. If they work together to do the work,what is the share of $R$ (in $Rs.$)?

Two men,$A$ and $B$,working together,completed a piece of work. If worked individually,it would have taken them $30$ and $40$ days to complete the work. If they have received a payment of $Rs. 2100$,then $B$'s share is (in $Rs.$)

Amit and Sujit together can complete a data entry assignment in $5$ days. Sujit's speed is $80\%$ of Amit's speed and the total key depressions in the assignment are $5,76,000$. What is Amit's speed in key depressions per hour if they work for $8$ hours a day?

$A$ and $B,$ working separately,can complete a piece of work in $9$ and $12$ days,respectively. If they work for a day alternately,$A$ beginning,in how many days will the work be completed?

$2$ men and $3$ women can complete a work in $10$ days,while $4$ men can complete it in $10$ days. In how many days will $3$ men and $3$ women complete the work?

While working $7$ hours a day,$A$ alone can complete a piece of work in $6$ days and $B$ alone in $8$ days. In what time would they complete it together,working $8$ hours a day? (in days)