A can do a piece of work in 30 days. He works at it for 5 days and then B finishes it in 20 days. In what time can A and B together it?  Select the correct option.
A) 53 1/3 days  B) 13 1/3 days  C) 23 1/3 days  D) 33 1/3 days  E) 53 1/7 days
Explanation:   5/30 + 20/x = 1   x = 24   1/30 + 1/24 = 3/40   40/3 = 13 1/3 days   Answer:13 1/3 days
<result>B</result>
A can do a piece of work in 30 days. He works at it for 5 days and then B finishes it in 20 days. In what time can A and B together it?