10 years ago the father was 35, the mother was 33,
the girl was 13 and the boy was 15, their average age was



Now, 10 years later, the father is 45, the mother is 43, 
the girl is now a woman 23, the boy is now a man 25.

7 years ago the wife had a baby boy, who is now 7 years old.
1 year ago the wife had a baby girl, who is now 1 year old.

Now their average age is also:



The average is the same, 24, and the baby is under 2 years of age.

But there are many other solutions as well.

Edwin