The average age of three boys is 25 years and their ages are in proportion 3:5:7. What is the age in years of the youngest boy?	Choose the correct choice from the following options:
A) 6  B) 9  C) 6  D) 4  E) 15
3x + 5x + 7x = 75   x =5   3x = 15   Answer:15
<result>E</result>
The average age of three boys is 25 years and their ages are in proportion 3:5:7. What is the age in years of the youngest boy?