Age of grandfather = x years
age of son = x months = y days
age of father = y weeks.
x months = x/12 years.
y days = x months = x/12 years.
y weeks = 7*y days = 7*x months = 7*x/12 years.
x years + y weeks + x months or y days = 140 years.
x years + 7*x/12 years + x/12 years = 140 years.
12*x/12 years + 7*x/12 years + x/12 years = 140 years.
12x+7x+x years/12 = 140 years.
20x/12 = 140
x = 140*12/20 = 84
So, age of grandfather = 84 years.
age of son = 84 months =7 years.
age of father = 140-7-84 = 49
age of father = 49.
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