The formula for perimeter is length + length + width + width
You know that all the sides of a square are equal to each other. That means that all the values in the perimeter formula should be the same. Therefore you can divide 72 by 4 (perimeter divided by the number of sides)
72 / 4 = 18
^^^Each side is 18 in
The formula for are is...
A = length x width
so...
18 * 18 = 324
324 in^2
Hope this helped!
~Just a girl in love with Shawn Mendes