The present ages of three persons are in proportions 4 : 7 : 9. Eight years ago, the sum of their ages was 56. Find their present ages (in years).

\par Let their present ages be 4x, 7x and 9x years respectively.

\par (4x - 8) + (7x - 8) + (9x - 8) = 56

20x = 80
x = 4

\par So, their present ages are 16 years, 28 years and 36 years.