Hey there!
I think that it safe to say that this room is a rectangular prism. Therefore, the top and bottom (floor and ceiling) have the same area. We see that our floor dimensions are 12 cm long and 7 cm wide. This also applies to the ceiling. Let’s take our two sides and multiply then to find our area.
12(7)=84
Therefore, the area is 84 square centimeters.
I hope that this helps!