A and B together can complete a work in 20 days. A is 20 percent more efficient than B, B alone can complete the same work in how many days?

44 days

A + B = 20 days,

Given,

A is 20 percent more efficient than B,Therefore

A : B 

6 : 5

⇒ Therefore, Total work = (6 + 5) x 20 = 11 x 20 = 220 units.  ..(Efficiency × Days = Total work)

⇒ Time required by B to complete the work alone = \(\frac{220}{5}\) = 44 days         ..(\(\frac{Work}{Efficiency}\) = Time)