$A$ can do a piece of work in $4 \, days$ and $B$ can do it in $12 \, days.$ In how many $days$ will they finish the work,both working together?

$10$ men can finish a piece of work in $10$ days,whereas it takes $12$ women to finish it in $10$ days. If $15$ men and $6$ women undertake to complete the work,how many days will they take to complete it?

$A$ can complete a work in $10$ days,$B$ can complete the same work in $20$ days,and $C$ in $40$ days. $A$ starts working on the first day,$B$ works on the second day,and $C$ works on the third day. Again,$A$ works on the fourth day,$B$ on the fifth day,and so on. If they continue working in the same way,in how many days will the work be completed?

$A, B$ and $C$ can do a piece of work in $24, 30$ and $40$ days respectively. They began the work together,but $C$ left $4$ days before the completion of the work. In how many days was the work done?

Some carpenters promised to do a job in $9$ days,but $5$ of them were absent and the remaining men did the job in $12$ days. The original number of carpenters was:

Sakshi can do a piece of work in $20$ days. Tanya is $25\%$ more efficient than Sakshi. The number of days taken by Tanya to do the same piece of work is