10 women can complete a work in 5 days and 10 children take 10 days to complete the work. How many days will 5 women and 10 children take to complete the work?
Choose the correct choice.
A) 4  B) 5  C) 7  D) 8  E) 2

Rationale: "1 women ' s 1 day work = 1 / 50 1 child ' s 1 day work = 1 / 100 ( 5 women + 10 children ) ' s 1 day work = ( 5 / 50 + 10 / 100 ) = 1 / 5 5 women and 10 children will complete the work in 5 days . b"
Answer: B