A set of 10 new questions in each round Question: ( 1 of 10 ) If John can finish the work in 6 days and Richard can finish the same work in 9 days, then in how many days both can finish the work together? (A) 3 3/5 days or 3.6 days (B) 15 days (C) 6 3/5 days or 6.6 days (D) 7.5 days