
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 polynomials $A$ and $B$ with respect to $x$, where $A=mx^{2}+2x-1$ and $B=x^{2}-nx+2$ ($m$ and $n$ are rational numbers).  
$(1)$ Simplify $3B-A$;  
$(2)$ If the result of $3B-A$ does not contain terms with $x$ or $x^{2}$, find the values of $m$ and $n$.

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