Answer: If you are looking for Area, use the formula A=length x width
If you are looking for Perimeter, use the formula P= 2(length x width)
Explanation:
So, the Area would be A=12x9 = 108 meters squared (you're multiplying 12 meters and 9 meters, which squares the unit)
and the Perimeter would be P= 2(12x9) = 216 meters