John is 30 because 60 / 2 = <<60/2=30>>30

Mary is fifteen because 30 / 2 = <<30/2=15>>15

Their total age is 105 because 60 + 30 + 15 = <<60+30+15=105>>105

Their average age is 35 because 105 / 3 = <<105/3=35>>35

# Answer

35
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
John is twice as old as Mary and half as old as Tonya. If Tanya is 60, what is their average age?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
35
John is twice as old as Mary and half as old as Tonya. If Tanya is 60, what is their average age?
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