
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
In response to the government's call to promote the construction of the "vegetable basket" project, a dealer invested $600,000 to build a vegetable production base. In the first year, various expenses amounted to $80,000, and the expenses incurred in each subsequent year were $20,000 more than the previous year. The annual income from vegetable sales was $260,000. Let $f(n)$ represent the net profit for the first $n$ years ($f(n) = $ total income for the first $n$ years $-$ total expenses for the first $n$ years $-$ investment). Then, $f(n) = $ \_\_\_\_\_\_ ($n$ represents \_\_\_\_\_\_); the dealer starts making a profit from the \_\_\_\_\_\_ year.

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