$A$ can do a job in $6 \, days$ and $A$ and $B$ can do it together in $2 \, days.$ How many $days$ will be taken by $B$ to do the job alone?

$A, B$ and $C$ can do a piece of work individually in $8, 12$ and $15$ days,respectively. $A$ and $B$ start working,but $A$ quits after working for $2$ days. After this,$C$ joins $B$ until the completion of the work. In how many days will the work be completed?

$39$ persons can repair a road in $12$ days working $5$ hours per day. In how many days will $30$ persons working $6$ hours per day complete the same work?

$5$ men can complete a work in $2$ days,$4$ women can complete the same work in $3$ days and $5$ children can do it in $3$ days. $1$ man,$1$ woman and $1$ child,working together,can complete the work in (in days):

$A$ and $B$ undertook to do a piece of work for $Rs. 4500$. $A$ alone could do it in $8$ days and $B$ alone in $12$ days. With the assistance of $C$,they finished the work in $4$ days. Then,$C$'s share of the money is (in $Rs.$)

$A$ and $B$ can do a piece of work in $12 \, \text{days}$ and $15 \, \text{days}$ respectively. They began to work together,but $A$ left after $4 \, \text{days}$. In how many more $days$ would $B$ alone complete the remaining work?