A can work four times as fast as B. Together they can finish a job in 12 days. In how many days can A complete the job alone? Choose the correct choice from the following answers:
A) 14 B) 15 C) 16 D) 17 E) 18
B's rate is x and A's rate is 4x.   x + 4x = 1/12   x = 1/60   A's rate is 4x = 1/15   A can complete the job in 15 days.   The answer is 15.
<result>B</result>
A can work four times as fast as B. Together they can finish a job in 12 days. In how many days can A complete the job alone?