A is half good a work man as B and together they finish a job in 20 days. In how many days working alone B finish the job? Select the correct option
A) 98 days B) 30 days C) 17 days D) 18 days E) 19 days

Rationale: "wc = 1 : 2 2 x + x = 1 / 20 = > x = 1 / 60 2 x = 1 / 60 = > 30 days answer : b"
Answer: B