
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 tourist goes on a hike from point $A$ to point $B$ and back, completing the whole journey in 3 hours and 41 minutes. The road from $A$ to $B$ first goes uphill, then over flat ground, and finally downhill. What is the distance over the flat ground if the tourist's speeds are 4 km/h uphill, 5 km/h on flat ground, and 6 km/h downhill, and the distance $\mathrm{AB}$ is 9 km?

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