Question 313459
Hello, 
Let's have x represent the youngest and 2x will show the oldest. Now we can find the average by:
(x+13+15+2x)/4=14.5 Rewritten as:
(3x+28)/4=14.5 Multiply both sides by 4 to get:
3x+28=58 Subtract 28 and divide by 3 to get:
x=10 So the youngest is 10 years old the oldest is 20. 
Make sense?
RJ
www.math-unlock.com