$A$ can finish a work in $18$ days and $B$ can do the same work in half the time taken by $A$. Then,working together,what part of the same work can they finish in a day?

$A$ and $B$ can together complete a task in $18$ hours. After $6$ hours, $A$ leaves. $B$ takes $36$ hours to finish the rest of the task. How many hours would $A$ have taken to do the task if he worked alone?

$10$ men can complete a piece of work in $15$ days and $15$ women can complete the same work in $12$ days. If all the $10$ men and $15$ women work together,in how many days will the work get completed?

$A$ can lay railway track between two given stations in $16 \, days$ and $B$ can do the same job in $12 \, days$. With the help of $C$,they did the job in $4 \, days$ only. Then $C$ alone can do the job in (in $days$)

$A$ job can be completed by $12$ men in $12$ days. How many extra days will be needed to complete the job if $6$ men leave after working for $6$ days?

$A$ can do a piece of work in $15 \text{ days}$. With the help of $A$,$B$ can do it in $6 \frac{2}{3} \text{ days}$. $B$ can do it alone in (in $\text{days}$)