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?
How many years of experience did James have 8 years ago? ** 8 years ago James had 20-8=<<20-8=12>>12 years
How many years of experience did John have 8 years ago? ** So 8 years ago John had 12*2=24 years experience
How many years of experience does John have now? ** That means John has 24+8=<<24+8=32>>32 years experience
How many years of experience does Mike have? ** So Mike has 32-16=<<32-16=16>>16 years of experience
How many years of experience do James, John, and Mike have together? ** So together they have 20+32+16=<<20+32+16=68>>68 years experience
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