First find the total tip amount: 20% * $200 = $<<20*.01*200=40>>40

Then subtract the friend's contribution: $40 - $10 = $<<40-10=30>>30

# Answer

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<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Mark wants to tip his server 20% on a $200 check. If his friend agrees to kick in $10, how much should Mark add?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
30
Mark wants to tip his server 20% on a $200 check. If his friend agrees to kick in $10, how much should Mark add?
train