x2------>
A).the area of the original design.
Rememeber that x= original width. Since it's a square, length equals width. The area of a square is any side squared, so the area is x².
x------->
C) The width of the new design. The width doesn't change, only the length does, and x has been defined as the original width. Therefore, x is both the orinignal width and the width of the new design.
x + 20------->
B) The length of the new design. In the original design, which is a square, x = width = length. When the designer increased the length by 20, the new length is x + 20.
20------->
D) The difference in the lengths of the designs. The length increases by 20, so 20 is the difference in the lengths of the original and new design.