A set of 10 new questions in each round. Question: ( 1 of 10 ) Joseph can finish a work in 19 days. Charles can finish the same work in 24 days while Christopher can finish the work in 29 days. How long will it take to finish it if they work together? (A) 7 1303/1703 days or 7.765 days (B) 24 days (C) 18 days (D) 14 1303/1703 days or 14.765 days