Which expression is equivalent to the area of metal sheet required to make this square-shaped traffic sign?

a square shaped traffic sign is shown with length of one side labeled as 8x minus 2.

Given:
square shaped traffic sign. side measure of 8x - 2

A square has 4 equal sides. To find the area of a square, simply square the measure of 1 side. 

Area of a square = a²
A = (8x-2)²
A = (8x-2)(8x-2)
A = 8x(8x-2) - 2(8x-2)
A = 64x² - 16x - 16x + 4
A = 64x² - 32x + 4

127 millimeters is the answer