1-Time and work

A can do a certain job in 12 days. B is 60% more efficient than A, B can do the work alone in ---------- 



Answer
In 1 day A will do 1/12th part of the work.
In 1 day B will do (1/12) x 1.6 = 16/120 =2/15.
So, B can do the work in 15/2 days = 7.5 days.