If $16$ men or $20$ women can do a piece of work in $25$ days,in what time will $28$ men and $15$ women do it? (in days)

$45$ men can complete a work in $16$ days. Four days after they started working,$36$ more men joined them. How many days will they now take to complete the remaining work?

$250$ men can finish a work in $20 \, \text{days}$ working $5 \, \text{hours}$ a day. To finish the work within $10 \, \text{days}$ working $8 \, \text{hours}$ a day,the minimum number of men required is:

$A$ can do a piece of work in $4 \, days$ and $B$ can do it in $12 \, days.$ In how many $days$ will they finish the work,both working together?

$60$ men could complete a work in $250$ days. They worked together for $200$ days. After that,the work had to be stopped for $10$ days due to bad weather. How many more men should be engaged to complete the work on time?

$A, B$ and $C$ can do a piece of work in $24, 30$ and $40$ days respectively. They began the work together,but $C$ left $4$ days before the completion of the work. In how many days was the work done?