Answer:
Area = 100x^2 + 80x + 16
Explanation:
Since a square's sides all should be congruent, divide (40x+16) by 4 since a square has 4 sides.
Each side would be 10x+4 after the division.
Area is lengthxwidth so it would be (10x+4) x (10x+4)
Area is 100x^2 +40x+40x+16 = 100x^2 + 80x + 16