Not enough info or diagram given.....
Suppose the square is 5 x 5 perimeter = 20 area = 25
Rectangle could be 9 x 1 Perimeter = 20 area = 9
Rectangle could be 8x 2 perimeter = 20 area = 16
rectangle could be 4 x 6 perimeter = 20 area = 24
etc.....
Need diagram or more info.....See what I mean?