Shashi can do a piece of work in $20$ days. Tanya is $25\%$ more efficient than Shashi. The number of days taken by Tanya to do the same piece of work is

$A$ and $B$ can complete a piece of work in $45$ and $40$ days,respectively. They began the work together,but $A$ leaves after some days and $B$ completed the remaining work in $23$ days. After how many days did $A$ leave?

$A$ and $B$ complete a job in $12 \text{ days}$,while $A, B$,and $C$ can complete it in $8 \text{ days}$. $C$ alone will finish the job in (in $\text{days}$):

Five men and $2$ boys,working together,can complete four times as much work per hour as a man and a boy working together. The ratio of the work completed by a man and a boy is:

$A$ can do a work in $12 \, days$. When he had worked for $3 \, days$,$B$ joined him. If they complete the work in $3$ more $days$,in how many $days$ can $B$ alone finish the work?

$5$ men and $5$ women earn $Rs. 660$ in $3$ days. $10$ men and $20$ women earn $Rs. 3500$ in $5$ days. In how many days can $6$ men and $4$ women earn $Rs. 1060$?