
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 shop increased the original price of a book by a certain percentage and then decreased the new price by the same percentage. After these changes, the final price of the book was $90\%$ of the original price. What was the percentage by which the price was increased and then decreased?
A) 15%
B) 20%
C) 25%
D) 30%
E) 32%

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