Below is an instruction that describes a task. Write a response that appropriately completes the request in English. Please answer in English.

### Instruction:
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?

### Response:
His rent is 900*12=$<<900*12=10800>>10,800 a year
He gets 3*400=$<<3*400=1200>>1200 per month
That means he makes 1200*12=$<<1200*12=14400>>14,400 per year
So his profit is 14400-10800=$<<14400-10800=3600>>3600 per year
#### 3600