The problem isn't stated correctly or completely:
"Paul was a child for 1/12 of his life a child for 1/6 of his life"
That has him being a chid for both 1/12 and 1/6 of his life.
3 years after his marriage he had a daughter
when he died his only grandson was 2 years old
This doesn't tell us how old his daughter was when she had the son.
It would make 10 years difference in the man's age if she were 20
or 30 then. We would have to know that to work the problem.
If you want to restate the problem in the thank-you note for,
copying it carefully, then we can halp you. There is not enough
information as it is.
Edwin