A and B can do a work in 15days, B and C in 30days, C and A in 45days. If A,B and C work together , they will complete the work in?	Choose one:
A) 10 days	B) 16 days	C) 20 days	D) 25 days	E) 22 days

Rationale: "a + b 1 day work = 1 / 15 b + c 1 day work = 1 / 30 c + a 1 day work = 1 / 45 adding we get 2 ( a + b + c ) = 1 / 15 + 1 / 30 + 1 / 45 = 11 / 90 a + b + c 1 day work = 11 / 180 a , b , c can finish the work in 180 / 11 days = 16 days approximately answer is b"
Answer: B