$7$ men can complete a piece of work in $12$ days. How many additional men will be required to complete double the work in $8$ days?

$20$ men can complete a piece of work in $16$ days. After $5$ days from the start of the work,some men left. If the remaining work was completed by the remaining men in $18 \frac{1}{3}$ days,how many men left after $5$ days from the start of the work?

$A$ and $B$ can complete a piece of work in $45$ and $40$ days respectively. Both started to work together,but after some days $A$ left and $B$ alone completed the remaining work in $23$ days. For how many days did $A$ work?

$4$ mat-weavers can weave $4$ mats in $4$ days. At the same rate,how many mats would be woven by $8$ mat-weavers in $8$ days?

$8$ children and $12$ men complete a certain piece of work in $9$ days. If each child takes twice the time taken by a man to finish the work,in how many days will $12$ men finish the same work?

$A$ can finish a work in $24 \, days$,$B$ in $9 \, days$,and $C$ in $12 \, days$. $B$ and $C$ start the work but are forced to leave after $3 \, days$. The remaining work was done by $A$ in (in $days$):