
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
Estelle's notebook contains 100 pages printed on 50 sheets, with two pages per sheet (pages 1 and 2, pages 3 and 4, and so forth). One morning, Estelle’s classmate borrows a set of consecutive sheets from her notebook. Later, it is found that the average (mean) of the page numbers on the remaining sheets of her notebook is exactly 49. How many sheets did her classmate borrow?
**A)** 8  
**B)** 10  
**C)** 12  
**D)** 15

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