A father has a 12 year old son. He was thrice his son's present age when the son was born. How old is the father now?

Present age of son = 12 years.

When the son was born, the father's age was three times the son's current age.

Let the present age of the father be F years.

When the son was born, the son's age was 0 years, and the father’s age was F − 12 years (since the son is now 12 years old).

Now, According to the question,

F – 12 = 3 × 12.

F - 12 = 36

F = 36 + 12 = 48

Thus, The father is 48 years old now.