
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
The initial cost of a car is 150,000 yuan, and the annual expenses for insurance, tolls, and gasoline are about 15,000 yuan. The annual maintenance cost for the first year is 3,000 yuan, which increases by 3,000 yuan each subsequent year. What is the optimal number of years to use the car (i.e., the number of years after which the average annual cost is minimized)?

Present the answer in LaTex format: \boxed{Your answer}
user