
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
Given the function $f(x)$ has the domain of $\mathbb{R}$, and for any $x \in \mathbb{R}$, $f(x) = f(x+6)$. Also, $f(x)$ is monotonically decreasing in the interval $(0,3)$, and the graph of $f(x)$ is symmetric about the line $x=3$. Determine the relationship between $f(1.5)$, $f(3.5)$, and $f(6.5)$.

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