The present ages of three persons are in the ratio of 4 : 7: 9. Eight years ago, the sum of their ages was 56. What are their present ages in years?

Let the present age of three persons are 4x, 7x and 9x years respectively.
Eight years ago, Ages of three person were 4x - 8, 7x - 8, 9x - 8 years.
According to question,
4x - 8 + 7x - 8 + 9x - 8 = 56
⇒ 20x - 24 = 54
⇒ 20x = 80
∴ x = 4
Hence, their present ages are
4 x 4 = 16 years,
7 x 4 = 28 years,
9 x 4 = 36 years respectively .