A can do a certain job in 20 days. B is 60% more efficient than A. How many days does B alone take to do the same job?	Choose the correct choice from the following answers:
A) 7 1/2 days  B) 8 days  C) 12 1/2 days  D) 9 days  E) None of them
Ratio of times taken by A and B = 160 : 100 = 8 : 5.   Suppose B alone takes x days to do the job.   Then, 8 : 5 :: 20 : x = 8x = 5 x 20 =x = 12 1/2 days.   Answer is 12 1/2 days.
<result>C</result>
A can do a certain job in 20 days. B is 60% more efficient than A. How many days does B alone take to do the same job?