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? Choose the correct answer.
A) 13 1/3 days
B) 8 days
C) 9 days
D) 63 days
E) 15 days
Explanation:   5/30 + 20/x = 1   x = 24   1/30 + 1/24 = 3/40   40/3 = 13 1/3 days   13 1/3 daysnswer 13 1/3 days
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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?