P, Q and R can do piece of work in 48, 60 and 80 days respectively. All three began to work together but P and Q left 12 and 16 days respectively before completion of the work. In how many days the work will be done?
P’s one day’s work = 1/48days Q’s one day’s work = 1/60days R’s one day’s work = 1/80days Then, (x -12)/48 + (x - 16)/60 + (x )/80 = 1 (5(x-12)+4(x-16)+3x)/240 = 1 5x – 60 + 4x – 64 + 3x = 240 12x = 240 + 124 12x = 364 x = 364/12 ∴x = 30(1/3) days
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