The are of a rectangle is calculated by multiplying the length and the width of the shape. First, we determine the dimensions of this figure. We do as follows:
Width = 12 - 2x - 2x = 12 - 4x
Length = 12 - x - x = 12 - 2x
Area = (Length)(Width)
Area = (12 - 2x )(12-2x)