Answer:
area = 27.5625, side length = 5.25
Explanation:
21 is the perimeter of a square (given). We know a square has 4 equal sides, so 4s = p, where s is the side length and p is the perimeter of a square. Thus: 4s = 21 → s = 5.25
We also know that a square has a = s², where s is the side length and a is the area. Thus, a = 5.25² → a = 27.5625