First find how many months Jason worked as a bartender: 9 years * 12 months/year = <<9*12=108>>108 months
Then find how many months Jason worked as a manager: 3 years * 12 months/year + 6 months = <<3*12+6=42>>42 months
Then add those two amounts to find his total amount of work experience: 108 months + 42 months = <<108+42=150>>150 months
#### 150