We know that a square has an equal height and width. So if all 4 sides, which are equal in length, add up to 12, then we can find the length of one side by dividing 12 by 4:
12/4= 3
If the length of one side is 3, we can multiply the height (3) by the width (3) to find the area.
3*3= 9
Answer: the area of the square is 9.