Karan, Arjun and Krunal alone can complete a work in 35,

Solution

Let the total work = 420 units (LCM of 35, 70 and 60) Amount of work done by Karan alone in one day = 420/35 = 12 units Amount of work done by Arjun alone in one day = 420/70 = 6 units Amount of work done by Krunal alone in one day = 420/60 = 7 units Amount of work done by Karan, Arjun and Krunal together in 3 days = 3 × (12 + 6 + 7) = 75 units Amount of work done by Arjun and Krunal together in 5 days = 5 × (6 + 7) = 65 units Remaining work = 420 – 75 – 65 = 280 units So, the time taken by Krunal alone to complete 280 units work = 280/7 = 40 days So, Krunal worked for 40 + 5 + 3 = 48 days