A is half good a work man as B and together they finish a job in 13 days. In how many days working alone B finish the job?	Choose one
A) 23
B) 22
C) 39 / 2
D) 36
E) 48

Rationale: c 39 / 2 wc = 1 : 2 2 x + x = 1 / 13 = > x = 1 / 39 2 x = 2 / 39 = > 39 / 2 days
Answer: C