5 men can do a piece of work in 6 days while 10 women can do it in 5 days. In how many days can 5 women and 3 men do it?

Answer: B. 5 days

Total effort is 30 man-days ( 5 X 6 ) or 50 woman-days ( 10 X 5 ).
Three men finish 1/10 of the work daily (3 out of 30 total units).
Five women also finish 1/10 of the work daily (5 out of 50 total units).
Together, they complete 2/10 (or 1/5) of the total job every day.
Since they finish 1/5 each day, the whole job takes 5 days to complete

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