
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 sells some pens on the first day. On the second day, the price of each pen is reduced by 1 yuan and 100 more pens are sold. On the third day, the price of each pen is increased by 3 yuan compared to the previous day, and 200 fewer pens are sold than on the previous day. If the amount of money made each day is the same, what is the price per pen on the first day (in yuan)?

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