
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 purchasing 400 units of a product at an original price of 80 yuan each, they can all be sold out at a price of 90 yuan each. It is known that for every 1 yuan increase in price per unit, the number of units sold decreases by 20. What should the selling price be to maximize profit?

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