10women can complete a work in 7days&10children take 14days to complete the work. How many days will 5women and 10children take to complete the work? Choose the correct choice from the following choices
A) 5 days  B) 7 days  C) 8 days  D) 9 days  E) 11 days

Rationale: 1 woman ' s 1 day ' s work = 1 / 70 1 child ' s 1 day ' s work = 1 / 140 5 women and 10 children 1 day work = ( 5 / 70 + 10 / 140 ) = 1 / 7 so 5 women and 10 children will finish the work in 7 days . b )
Answer: B