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)	Select the correct option:
A) 12, 14, 18	B) 14, 20, 36	C) 16, 12, 14	D) 16, 28, 36	E) None
Sol.   Let thier 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 16 years, 28 years and 36 years respectively.   Answer 16, 28, 36
<result>D</result>
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)