How To Solve The Square’s Length With “Outside The Box” Thinking!

In a square, a line is drawn from the bottom left corner with length 12 to the interior of the square. From the end of that line, a perpendicular is drawn going up and left with length 3. From the end of that line, another perpendicular is drawn going up and right with length 9. This line segment ends at the upper right corner of the square. What is the value of x, the square’s side length?

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