A set of 10 new questions in each round Question: ( 1 of 10 ) Mark can finish a work in 29 days. Donald can finish the same work in 30 days while Steven can finish the work in 31 days. How long will it take to finish it if they work together? (A) 18 2679/2699 days or 18.993 days (B) 30 days (C) 22.5 days (D) 9 2679/2699 days or 9.993 days