
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 $φ∈(-\frac{π}{2},\frac{π}{2})$, if the graph of the function $f\left(x\right)=\sin \left(3x+\varphi \right)$ is symmetric about the line $x=\frac{3π}{5}$, then the value of $\varphi$ is ______.

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