###Human: Eden's mom is twice as old as Eden, who is twice as old as Devin. If Devin is 12 years old, what's the average age of the three?, ### Assistant: If Devin is 12 years old, then Eden is 2 * 12 years = 24 years old.
Since Eden's mom two times older than Eden, her age is 24 years * 2 = 48 years.
In total, they have 48 years + 24 years + 12 years = 84 years
The average age for the three is 84 years / 3 people = 28 years/person 
 So the answer is :  28