He gets 3*$400=$<<3*400=1200>>1200 per month

So he gets 1200*12=$<<1200*12=14400>>14,400 per year

So he pays 12*900=$<<12*900=10800>>10800 a year

That means his profit is 14400-10800=$<<14400-10800=3600>>3600 per year

# Answer

3600
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
John sublets his apartment to 3 people who each pay $400 per month.  He rents the apartment for $900 a month.  How much profit does he make in a year?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
3600
John sublets his apartment to 3 people who each pay $400 per month.  He rents the apartment for $900 a month.  How much profit does he make in a year?
train