A is twice as good a workman as B and they took 9 days together to do the work B alone can do it in.  Choose the correct choice from the following choices
A) 17 days B) 12 days C) 29 days D) 25 days E) 27 days

Rationale: "wc = 2 : 1 2 x + x = 1 / 9 x = 1 / 27 = > 27 days answer : e"
Answer: E