8 years ago James had 20-8=<<20-8=12>>12 years

So 8 years ago John had 12*2=24 years experience

That means John has 24+8=<<24+8=32>>32 years experience

So Mike has 32-16=<<32-16=16>>16 years of experience

So together they have 20+32+16=<<20+32+16=68>>68 years experience

# Answer

68
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
James has 20 years of experience.  8 years ago John had twice as much experience as James.  Mike started when John had 16 years of experience.  What is their combined experience?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
68
James has 20 years of experience.  8 years ago John had twice as much experience as James.  Mike started when John had 16 years of experience.  What is their combined experience?
train