You can't tell from the information given in the question.
The perimeter doesn't tell you the area.
Here . . . look at this:
Dimensions Perimeter Area
1 x 9 20 9
1.5 x 8.5 20 12.75
2 x 8 20 16
2.5 x 7.5 20 18,75
3 x 7 20 21
3.5 x 6.5 20 22.75
4 x 6 20 24
4.5 x 5.5 20 24.75
5 x 5 20 25
