The age of Somu is one-third his father's. 6 years back he was one-fifth of his father's age. What is his persent age ?
Choose one
A) 11 B) 13 C) 14 D) 12 E) 10

Rationale: "explanation : let somu ' s age be x and that of his father be 3 x . so , x - 6 = 3 x - 6 / 5 = x = 12 answer : option d"
Answer: D