
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
When an item with a purchase price of 70 yuan is sold at a price of 80 yuan, 400 units can be sold per month. It is known that the fixed monthly expenses for rent and salaries are 500 yuan. It has also been found that if the selling price of the item is increased by 1 yuan from 80 yuan, the sales volume will decrease by 20 units. To achieve the maximum profit, what should the selling price be set at?

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