A set of 10 new questions in each round. Question: ( 1 of 10 ) If William can finish the work in 12 days and Matthew can finish the same work in 16 days, then in how many days both can finish the work together? (A) 14 days (B) 6 6/7 days or 6.857 days (C) 12 6/7 days or 12.857 days (D) 28 days