A and B, working together, can complete a work in d days. Working alone, A takes (8 + d) days and B takes (18 + d) days to complete the same work. A works for 4 days. The remaining work will be completed by B alone, in:

24 days

A + B = d days

A = (8 + d) days,

B = (18 + d) days,

⇒ d =  √(8 x18) = √144 = 12

⇒ d = 12, therefore, A = 8 + 12 = 20 days. B = 18 + 12 = 30 days,

⇒ A worked for 4 days = 3 x 4 = 12 days,

⇒ Remaining work = 60 - 12 = 48 units,

⇒ Time taken by B to complete the work = \(\frac{48}{2}\) = 24 days.   ..(\(\frac{Work}{Efficiency}\) = Time)