The average age of three boys is 12 years and their ages are in proportion 4:5:9. What is the age in years of the youngest boy?	Choose the correct choice.
A) 6 B) 9 C) 8 D) 4 E) 2
4x + 5x + 9x = 36   x =2   4x = 8   Answer: 8
<result>C</result>
The average age of three boys is 12 years and their ages are in proportion 4:5:9. What is the age in years of the youngest boy?