
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
Fengming Literary Society held a book sharing ceremony at school, where each student gave one book to each other member of the group. A certain group exchanged a total of 210 books. If there were $x$ students in the group, form the equation based on the given conditions.

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