A can complete the job in 6 hours and B can complete the same job in 3 hours. A works for 1 hour and then B joins and both complete the job. What fraction of the job did B complete	Choose the correct choice from the following answers
A) 1 / 9  B) 3 / 10  C) 1 / 2  D) 5 / 6  E) 8 / 9

Rationale: a = 1 / 9
Answer: A