If $28$ men complete $\frac{7}{8}$ of a piece of work in a week,then the number of men,who must be engaged to get the remaining work completed in another week is

$A$ takes twice as much time as $B$ or thrice as much time as $C$ to finish a piece of work. Working together,they can finish the work in $2$ days. $B$ can do the work alone in (in days):

Two workers $A$ and $B$ working together completed a job in $5$ days. If $A$ worked twice as efficiently as he actually did and $B$ worked $1/3$ as efficiently as he actually did,the work would have been completed in $3$ days. To complete the job alone,$A$ would require (in days):

$A$ certain sum of money is sufficient to pay wages for $21$ days of $X$ or $28$ days of $Y$. The money is sufficient to pay the wages of both for ........ days.

Sister can bake $50$ cakes in $25$ hours. Sister and Mummy together can bake $75$ cakes in $15$ hours. How many cakes can Mummy bake in $15$ hours?

Two men,$A$ and $B$,working together,completed a piece of work. If worked individually,it would have taken them $30$ and $40$ days to complete the work. If they have received a payment of $Rs. 2100$,then $B$'s share is (in $Rs.$)