A and B working together can do 45% of the work in 9 days. A alone can do the work in 30 days. How many days will B alone take to do the same work?

60 days

A + B = 45% of W = 9 days = 20 days,

A = 30 days,

⇒ A + B = 3, (Efficiency)

⇒ 2 + B = 3,

⇒ B = 1,

⇒ Time required by B to complete the work alone = \(\frac{60}{1}\) = 60 days,  ..(\(\frac{Work}{Efficiency}\) = Time)