If the longer side is 31.5", then the width is NOT 9".
ALL THIS is RUBBISH =======>-------width
You can find these:
perimeter
area,<======== You already KNOW who wrote this!
If the shorter side is 31.5", then the width is STILL NOT 9", and the above is STILL RUBBISH! ANY way you take it, it's nothing but RUBBISH!!!