Human: John drives 1000 miles a month. He needs to get an oil change every 3000 miles. He gets 1 free oil change a year. If an oil change costs $50, how much does he pay a year? Assistant: 
How many months does he need to get an oil change? ** He needs to get an oil change every 3000/1000 = <<3000/1000=3>>3 months
How many oil changes does he get a year? ** So he gets 12/3 = <<12/3=4>>4 oil changes a year
How much does he pay a year? ** That means he pays for 4-1 = <<4-1=3>>3 oil changes a year
How much does he pay a year? ** So he pays 3*$50 = $<<3*50=150>>150 a year
#### 150