Let the son’s present age be x years.

∴ Mother’s present age = (x + 25) years

After 8 years,

Son’s age = (x + 8) years

Mother’s age = (x + 25 + 8) = (x + 33) years .

Since, the ratio of the son’s age to mother’s age after 8 years is 4/9.

\(\cfrac{x+8}{x+33} =\cfrac{4}{9}\)

∴ 9 (x + 8) = 4 (x + 33)

∴ 9x + 72 = 4x + 132

∴ 9x – 4x = 132 – 72

∴ 5x = 60

∴ x = \(\cfrac{60}{5}\)

∴ x = 12

∴ Son’s present age is 12 years.