Given that Jack was 34 years old when his son Phillip was born. The sum of their age is now 50 years.
Let a be the present age of Jack's son.
The present age of jack is a+34
The sum of their age is 50.
The present age of Jack's son is 8 years.
The present age of Jack =8+34=42 years.
The present age of Jack is 42 years and his son's age is 8 years.