A, B and C can do a piece of work in 20 days, 25 days and 30 days respectively. If they work alternatively, then in how many days the work will be finished?

\(24\frac{4}{15}\)

As A , B & C works on alternate days . so work of 3 days = 15R + 12R + 10R

= 37R

work of 24 days = 8 × 37R = 296R

remaining work = 330R - 296R = 4R

Total work = Efficiency ×  Number of days

on 25th day , time taken by A to to do 4R work = \(\frac{4}{15}\)

Total time take = 24 + \(\frac{4}{15}\)  =  24\(\frac{4}{15}\) days