The sum of ages of 5 children born at the intervals of 3 years each is 60 years. What is the age of the youngest child?  Choose the correct choice from the following answers.
A) 3 years B) 4 years C) 6 years D) 7 years E) 8 years

Rationale: "let the ages of children be x , ( x + 3 ) , ( x + 6 ) , ( x + 9 ) and ( x + 12 ) years . then , x + ( x + 3 ) + ( x + 6 ) + ( x + 9 ) + ( x + 12 ) = 60 5 x = 30 x = 6 . age of the youngest child = x = 6 years . c )"
Answer: C