
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
A store purchases 1000 items at a price of 80 yuan per item (unsold items can be returned to the manufacturer). Market research indicates that when the selling price is set at 100 yuan per item, all items will be sold out. For every 1 yuan increase in the selling price, the sales volume decreases by 10 items. To maximize profit, the store decides to increase the selling price by x yuan, resulting in a total profit of y yuan.
(1) Please express y as a function of x;
(2) At what selling price will the total profit be maximized, and what is the profit at this price?

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