$A$ 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?

$A$ tyre has two punctures. The first puncture alone would have made the tyre flat in $9 \,minutes$ and the second alone would have done it in $6 \,minutes.$ If air leaks out at a constant rate,how long does it take both the punctures together to make it flat? (in $minutes$)

Bindal can finish a work in $10$ days. Jindal is twice as efficient as Bindal. If they work together,in how many days will the work be completed?

$A$ can do a piece of work in $8$ days. $A$ undertook it for $Rs. 320$. With the help of $B$,he finishes the work in $6$ days. $B$'s share is (in $Rs.$):

$A$ can do a piece of work in $12$ days and $B$ in $20$ days. If they together work on it for $5$ days and the remaining work is completed by $C$ in $3$ days, then in how many days can $C$ do the same work alone?

$A$ and $B$ can separately complete a piece of work in $20$ days and $30$ days respectively. They worked together for some time,then $B$ left the work. If $A$ completed the rest of the work in $10$ days,then for how many days did $B$ work?