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).
Answer: B
Let their present ages be \(4x, 7x \) and \(9x\) years respectively
Then, \((4x - 8) + (7x - 8) + (9x - 8) = 56\)
\(\Rightarrow 20x = 80\)
\(\Rightarrow x=4\)