A is half good a work man as B and together they finish a job in 18 days. In how many days working alone B finish the job?  Choose the most appropriate option.
A) 23	B) 22	C) 27	D) 36	E) 48

Rationale: "c 27 wc = 1 : 2 2 x + x = 1 / 18 = > x = 1 / 54 2 x = 1 / 27 = > 27 days"
Answer: C