A and B working together can do 30% of the work in 6 days. B alone can do the same work in 25 days. How long will A alone take to complete the same work?

100 days

A + B = 30% Of W = 6 days = 20 days,

B = 25 days,

⇒ A + B = 5, (Efficiency)

⇒ A + 4 = 5,

⇒ A = 1,

⇒ Time required by A to complete the total work alone = \(\frac{100}{1}\) = 100 days,   ..(\(\frac{Work}{Efficiency}\) = Time)