
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
The ancient Chinese book "Nine Chapters on the Mathematical Art" recorded a problem as follows: "Today, a group of people jointly buy pigs. If each person contributes $100$ coins, there will be an excess of $100$ coins; if each person contributes $90$ coins, it will be just enough." If there are a total of $x$ people, according to the problem, the equation can be written as ____.

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