
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
Let $f(x)$ be a function defined on $\mathbb{R}$ with a period of 6, which is monotonically decreasing in the interval $(0,3)$, and the graph of $y=f(x)$ is symmetric about the line $x=3$. Determine the correct order of the values $f(1.5)$, $f(3.5)$, and $f(6.5)$.

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