
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
The transformation corresponding to the second-order matrix $M$ maps the points $(1, -1)$ and $(-2, 1)$ to $(-1, -1)$ and $(0, -2)$, respectively.  
(Ⅰ) Find the inverse matrix $M^{-1}$ of the matrix $M$;  
(Ⅱ) Suppose the line $l$ is transformed into line $m$ under the transformation $M$: $2x-y=4$, find the equation of line $l$.

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