The present ages of three persons in proportions 4 : 7 : 9. Eight years ago, the sum of their ages was 56. Find their present ages (in years).  Choose the correct answer:
A) 8, 20, 28
B) 16, 28, 36
C) 20, 35, 45
D) 18, 24, 32
E) None of these
Explanation:   Let their present ages be 4x, 7x and 9x years respectively.   Then, (4x - 8) + (7x - 8) + (9x - 8) = 56   20x = 80   x = 4.   Their present ages are 4x = 16 years, 7x = 28 years and 9x = 36 years respectively.   Answer: 16, 28, 36
<result>B</result>
The present ages of three persons in proportions 4 : 7 : 9. Eight years ago, the sum of their ages was 56. Find their present ages (in years).