A father’s age at the time of the birth of his son is the same as the present age of the son. If the age of the son was 15 years five years ago, then what is the current age of the father?

40 years

So Let,

--> The present age of father be 'F'

--> The present age of son be 'S'

=> F - S = S

=> F = S +S

=> F = 2 x S

Now, If the age of the son was 15 years five years ago,

=> S-5 =15

= S = 20 years.

Then, F = 2 × 20

--> F = 40 years

Thus, the current age of the father is 40 years.