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

$2$ men and $4$ boys can do a piece of work in $10$ days,while $4$ men and $5$ boys can do it in $6$ days. Men and boys are paid wages according to their output. If the daily wage of a man is $Rs. 40$,then the ratio of daily wages of a man and a boy will be

$A$ 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?

$A, B$ and $C$ together earn $Rs. 2700$ in $18$ days. $A$ and $C$ together earn $Rs. 940$ in $10$ days. $B$ and $C$ together earn $Rs. 1520$ in $20$ days. Find the daily earning of $C$ (in $Rs.$).

$A$ worker can complete a piece of work in $50$ days. On the first day,he works alone. On the second day,one more person joins him,on the third day,one more person joins them,and this process continues until the work is completed. How many days are needed to complete the work?

$P$ and $Q$ working together can complete a certain work in $6 \, \text{days}$. $Q$ alone can do it in $8 \, \text{days}$. In how many $\text{days}$ could $P$ alone finish the same work?