A father is nine times as old as his son and the mother is eight times as old as the son. The sum of the father's and the mother's age is 51 years. What is the age of the son?

 a) 7 years
 b) 5 years
 c) 4 years
 d) 3 years

Civil Services-2015

3 years. Solution Let age of son = x Father's age = 9x Mother's age = 8x Sum of age of father and mother = 9x + 8x =51 x = 3