Answer:
The area of the shaded region is
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Step-by-step explanation:
For now, let's ignore the 4 by 4 smaller square.
The orange larger square has area of...
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You can use the FOIL rule to get the same result. The box method is also a visual handy tool.
No matter which method you use, the area of the orange square is
if we ignore the 4 by 4 portion.
However, we do have that white portion to take away from the orange square. So we'll subtract off 4*4 = 16 square units to end up with

The orange shaded region has area of
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If we knew what the value of x was, then we could find an actual numeric result rather than a polynomial like this.