$6$ men or $12$ women can do a piece of work in $20$ days. In how many days can $8$ men and $16$ women do twice as big as this work?

Nikita,Nishita,and Kavita can complete a work in $2 \frac{2}{3}$ days. If Nishita and Kavita can complete it in $4$ days,and Nishita alone can do it in $6$ days,then in how many days can Nikita and Nishita complete the work?

$A$ can do a certain work in $12$ days. $B$ is $60\%$ more efficient than $A$. How many days will $B$ and $A$ together take to do the same job?

$A$ and $B$ can complete a piece of work in $18$ days; $B$ and $C$ in $24$ days; $C$ and $A$ in $36$ days. $A$ alone can complete the work in (in days):

$A$ completes a piece of work in $4 \text{ days}$ and $B$ completes it in $6 \text{ days}$. If they both work on it together,then the number of days required to complete the same work is (in $\text{days}$):

$5$ men can complete a work in $2$ days,$4$ women can complete the same work in $3$ days and $5$ children can do it in $3$ days. $1$ man,$1$ woman and $1$ child,working together,can complete the work in (in days):