A is half good a work man as B and together they finish a job in 12 days. In how many days working alone B finish the job?
Choose the correct choice from the following options:
A) 23 B) 22 C) 18 D) 36 E) 48

Rationale: "c 18 wc = 1 : 2 2 x + x = 1 / 12 = > x = 1 / 36 2 x = 1 / 18 = > 18 days"
Answer: C