Step-by-step explanation: The area for the square is 12x12 or 144. The area for a triangle is base x height x 1/2. Therefore, that would be 12 x 10 x 1/2 or 60. There are 4 sides to this pyramid, so 60 x 4 = 240. We then add 144 and 240 to get 384 sq. mm.
