A can do a job in 8 days and B can do it in 20 days. A and B working together will finish twice the amount of work in ------- days?	Choose the correct option:  A) 21 ½ days  B) 11 3/7 days  C) 23 ½ days  D) 12 ½ days  E) None of these
Explanation:   1/8 + 1/20 = 7/40   40/7 = 40/7 *2 = 11 3/7 days   Answer: 11 3/7 days
<result>B</result>
A can do a job in 8 days and B can do it in 20 days. A and B working together will finish twice the amount of work in ------- days?