The measure of an interior angle of a regular n-sided polygon is calculated as $\frac{(n-2) \cdot 180^{\circ}}{n}$.
A hexagonal piece of paper with red-colored side lengths of 1 unit and black-colored side lengths of x units is cut along two lines parallel to the red-colored sides as shown in the figure to obtain a regular hexagon with a side length of 3 units.
According to this, what is x?
A) 3.5
B) 4
C) 4.5
D) 5
E) 5.5