A can do a piece of work in 4 days. B can do it in 6 days. With the assistance of C they completed the work in 2 days. Find in how many days can C alone do it? Choose the correct choice from the following:
A) 87 days
B) 12 days
C) 66 days
D) 77 days
E) 44 days

Rationale: c = 1 / 2 - 1 / 4 - 1 / 6 = 1 / 12 = > 12 days answer : b
Answer: B