A can finish a work in 20 days and B can finish the same work in 25 days. They begin together, but B left the work after 5 days. How many more days will A take to finish the remaining work?

11

A = 20 days,  B = 25 days,

⇒ A + B worked for 5 days = (5 + 4) x 5 = 45 units,   ..(Efficiency × Days = Total work)

⇒ Remaining work = 100 - 45 = 55 units,

⇒ Time required by A to complete the 55 units alone = \(\frac{55}{5}\) = 11 days.      ..(\(\frac{Work}{Efficiency}\) = Time)

Therefore, A will complete the remaining work in 11 days.