A is half good a work man as B and together they finish a job in 14 days. In how many days working alone B finish the job?
Choose the correct choice from the following options.
A) 23  B) 22  C) 21  D) 36  E) 48

Rationale: "c 21 wc = 1 : 2 2 x + x = 1 / 14 = > x = 1 / 42 2 x = 1 / 21 = > 21 days"
Answer: C