12 men and 18 boys working $$7\frac{1}{2}$$ hours a day can do a certain work in 60 days. If one man works equal to 2 boys. Then the number of boys required to help 21 men to do twice the work in 50 days, working 9 hours a day, will be
2 boys = 1 man
So, 21 men can do work W is 60 days working 7.5 hours per day.
to do 2W, 42 men are needed.
To do the job in 50 days, 60 x 42 / 50 men are needed.
To do the job working 9 hours a day, 7.5/9 x 60 x42/50 men are needed
= 42 men
We only have 21 men so, we get 42 extra boys to get the work needed for the 21 extra men.
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