Briefly

Grandfather, father and son

Grandfather, father and son

I have as many weeks as days my son has. My son is as many months old as my father is and we all add up to three years.

How old was my father when my son was born?

Solution

If we call TO at the age of grandfather, P at the age of the father and H at the age of the child, it is fulfilled that:

P = 7 × H
A = 12 × H
A + P + H = 100

For what substituting we have:

7 × H + 12 × H + H = 100

where we get that H = 5, P = 35 and A = 60. And in response to the question, my father was 55 when my son was born.