Question 379759
Let m be the man's age and s be the son's age NOW.  (always set up age problems in the now...)
Thus m = 3s.  We also know he is 30 years older, or m = s + 30.
We can set them equal and get
m = 3s
m = s + 30
Therefore,
3s = s + 30
2s = 30
s = 15