
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 road from home to school takes Sergei 30 minutes. One day, on his way, he remembered that he had forgotten his pen at home. Sergei knew that if he continued to the school at the same speed, he would arrive there 9 minutes before the bell rings, but if he returned home for the pen and then continued to school at the same speed, he would be 11 minutes late for the lesson. What fraction of the way did he cover?

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