Solution:From quantity I,
A = 1/36
A + B = 1/24 days
B = 1/24 - 1/36
B = 1/72
C = 7/120 - 1/24 = 1/60
LCM of 36, 72, 60 = 1080
Work done by A alone in a day = 1080/36 = 30 units
Work done by B alone in a day = 1080/72 = 15 units
Work done by C alone in a day = 1080/60 = 18 units
After three days = 30 + 15 + 18 = 63 units of work is completed
After 51 days = 63 × 17 = 1071
A alone complete 9 units of work in 9/30 = 3/10 days
Total time = 51 (3/10) days
From quantity II,
A = 100/60 × 54 = 90 days
B = 2/1 × 30 = 60
C = 90
{(x + 10)/90} + {(x + 10)/60} + {x/90} = 1
2x + 20 + 3x + 30 + 2x = 180
7x = 130
x = 130/7
Total time = 10 + 130/7 = 28 (4/7) days
Quantity I > quantity II