A,B,C can complete a piece of work in 18,6,12 days. Working together, they complete the same work in how many days?	Choose the correct choice from the following answers:	A) 2	B) 4 / 5	C) 7 / 9	D) 36 / 11	E) 24 / 7

Rationale: "a + b + c 1 day work = 1 / 18 + 1 / 6 + 1 / 12 = 11 / 36 a , b , c together will complete the job in 36 / 11 days answer is d"
Answer: D