A can work three times as fast as B. Together they can finish a job in 12 days. In how many days can A complete the job alone? Options.
A) 14
B) 16
C) 18
D) 20
E) 22
B's rate is x and A's rate is 3x.   x + 3x = 1/12   x = 1/48   A's rate is 3x = 1/16   A can complete the job in 16 days.   The answer is 16.
<result>B</result>
A can work three times as fast as B. Together they can finish a job in 12 days. In how many days can A complete the job alone?