
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
Xiao Ming bought a book, and his classmates wanted to know the price of the book. Xiao Ming asked them to guess. Classmate A said, "At least $20." Classmate B said, "At most $15." Xiao Ming said, "You are both wrong." Therefore, the price $x (\text{yuan})$ of this book is in the range of ______.

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