$A$ 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:

$A$ man and a boy received $Rs. 800$ as wages for $5$ days for the work they did together. The man's efficiency in the work was three times that of the boy. What are the daily wages of the boy? (in $Rs.$)

Subhash can copy $50$ pages in $10$ $h$,Subhash and Prakash can copy $300$ pages in $40$ $h$. In how much time can Prakash copy $30$ pages? (in $h$)

$A$ can do a work in $20 \, days$ and $B$ in $40 \, days$. If they work on it together for $5 \, days$,then the fraction of the work that is left is:

$P$ can complete $\frac{1}{4}$ of a work in $10$ days,$Q$ can complete $40\%$ of the same work in $15$ days,$R$ can complete $\frac{1}{3}$ of the work in $13$ days,and $S$ can complete $\frac{1}{6}$ of the work in $7$ days. Who will be able to complete the work first?

$A$ and $B$ can together finish a work in $30$ days. They worked together for $20$ days and then $B$ left. After another $20$ days,$A$ finished the remaining work. In how many days can $A$ alone finish the job?