Answer:
270
Step-by-step explanation:
-6 multiply 5 gives you -30
-3 multiply -3 gives you -9
-30 multiply 9 gives you
-270
As there are 81 tiles total, that makes your area 81. Being a square, that makes your area equation A=s^2. As you need a side, this makes your equation s=√A. Plugging in 81 as A, we get s=√81=9, so an edge has 9 tiles.