Perimeter is 2(length) + 2(width).
Since the length is equal to the width in a square, the perimeter is simply 4(length).
So, divide 140 by 4 to get side length.
140/4 = 35
Each side is 35.
A= l*w (length * width)
Since we know already that length and width are equal in a square, A = l^2 in a square.
35^2 = 35*35 = 1225.
So, the area of the square is 1225 square inches (in^2)