Chain Rule

Construction of a road was entrusted to a civil engineer. He was to finish the work in $124$ days for which he employed $120$ workmen. Two-thirds of the work was completed in $64$ days. How many workmen can be removed now without affecting the completion of the work on time?

$40$ persons take $6 \mathrm{days}$ to complete a certain task working $10 \mathrm{hours}$ a day. How many hours a day will be sufficient for $30$ persons to complete the same task in $10 \mathrm{days}?$

If $10$ men can reap $40$ hectares of a field in $5$ days then how many hectares of field can $30$ men reap in $10$ days?

A job that can be completed by $2$ men and $6$ women in $10$ days will be completed by $4$ men and $12$ women in how many days?

In a school, there is a meal for $60$ girls or $100$ boys. If $50$ boys have taken their meal, how many girls will be catered with the remaining meal?

An army camp of $6600$ men had provisions for $64$ days, when given at the rate of $850$ grams per head. At the end of $14$ days, a troop arrives and it was found that the provisions will last $34$ days more, when given $825$ grams per head. What is  the strength of new troop?

If $12$ pumps can raise $4800$ tonnes of oil in $10$ days, working $8$ hours a day, in how many days will $16$ pumps raise $6000$ tonnes of oil, working $12$ hours a day?

If $10$ laborers can dig a well $40 m$ deep in $18$ days, working $9$ hours a day, how  many additional laborers should be engaged to dig a similar well $80 m$ deep in $6$  days, each laborer working $9$ hours a day?

$28$ pipes can empty a tank in $4$ days working $8$ hours a day. If $84$ pipes are used  to for $5$ hours each day, then the same work will be completed in

In a dairy farm, $20$ horses eat $40$ bags of husk in $40$ days. In how many days $10$  horses will eat $30$ bags of husks?

A contractor employed $60$ men to do a piece of work in $76$ days. After $50$ days, he  employed $10$ more men and the work was finished $2$ day earlier. How many days  he would have been behind, if he had not employed additional men?

A contractor undertakes to do a job in $18$ days. He employees certain number of men, but $12$ of them being absent from the very first day, the rest can complete  the work in $30$ days. The number of men originally employed? 

$2$ men or $4$ women or $5$ children can complete a piece of work in $38$ days. In how many days will $1$ man, $1$ woman and $1$ child complete the same work?

Work is to be completed. $10$ men started the work and completed ${\frac{1}{6}}^{th}$ of the work in $5$ days working $3$ hrs each day. $2$ more men are employed. In how many days will the total number of men complete four times work as before working $5$ hours each day?

$20$ carpets are to weave by $40$ women in $50$ days working $8$ hours per day. After $20$ days, order of $6$ more carpets came. To complete the total work on time, how many more hours per day they will have to work?

$10$ women completed ${\frac{2}{7}}^{th}$ of work in $18$ days working $6$ hours each day. After this $5$5 women left and $2$ men joined. In how many days working same number of hours, the remaining work will get completed if $1$ man is equal to $2$ women?

A job is completed by $5$ men or $7$ women in $40$ days, then in how many days thrice the job as previous will be completed by $5$ men and $3$ women?

There is sufficient food for $40$ men for a $15$ days picnic. If after $6$ days $4$ men leave, how many more days can the remaining men intake food?

$2$ men and $4$ women can complete a job in $5$ days. Also same job can be completed by $3$ men and $8$ women in $3$ days. In how many days, twice the job can be completed by $3$ men and $3$ women?

A job that can be completed by $2$ men and $6$ women in $10$ days will be completed by $5$ men and $15$ women in how many days?