
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
Jiaqi is ready to solve the problem: solving the system of linear equations $\left\{\begin{array}{c}x-y=4\\□x+y=8\end{array}\right.$ but finds that the coefficient "$\square$" is unclearly printed.<br/>$(1)$ Jiaqi guesses that "$\square$" is $3$, then the solution to the system of linear equations is ______；<br/>$(2)$ Mom says, "You guessed wrong, I saw that the standard answer for $x$ and $y$ is a pair of opposite numbers." Then the value of "$\square$" in the original problem is ______.

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