Efficiency: A = 1/12, B = 1/15, C = 1/20. Total = $(5+4+3)/60 = 12/60 = 1/5$. Time = 5 days.
क्षमता: A = 1/12, B = 1/15, C = 1/20। कुल = $(5+4+3)/60 = 12/60 = 1/5$। समय = 5 दिन।