Aptitude Hack#136(9-7-19)

Question:

The present ages of A, B and C are in proportions 4:5:9. Nine years ago, the sum of their ages was 45 years. Find their present ages in years

A)15,20,35
B) 20,24,36
C) 20,25,45
D) 16,20,36

Answer: D)  16,20,36

Explanation: 
Let the current ages of A, B, and C be a 
4x years, 5x years and 9x respectively.
Then (4x-9) + (5x-9) + (9x-9) =45
∴ 18x – 27 = 45
∴ 18x = 72
∴ x = 4
Present ages of A, B and C are
 4x = 16, 5x = 20, 9x = 36 respectively.