A can do a certain job in 12 days. B is 60% more efficient than A. The number of days it takes for B to do the same piece of work, is:_________?

A. 12/6 days
B. 15/2 days
C. 23 days
D. 34 days

Ratio of time, taken by A and B = 160 : 100 = 8 : 5
If A takes 8 days, B takes 5 days.
If A takes 12 days, B takes = [5/8×12]=15/2 days