$A$ can do a work in $10 \text{ days}$ and $B$ in $20 \text{ days}$. If they work together on it for $5 \text{ days}$,then the fraction of the work that is left is:

$A$ alone can complete a work in $18 \, days$ and $B$ alone in $15 \, days.$ $B$ alone worked at it for $10 \, days$ and then left the work. In how many more days will $A$ alone complete the remaining work?

Sunil completes a work in $4$ days,whereas Dinesh completes the work in $6$ days. Ramesh works $1 \frac{1}{2}$ times as fast as Sunil. The three together can complete the work in (in days):

$A$ 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?

$A$ piece of work was to be completed in $40$ days. $A$ number of men employed upon it did only half the work in $24$ days. $16$ more men were then set on,and the work was completed in the specified time. How many men were employed at first?

$A, B$ 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?