(A) Surface area can be solved by simply finding the area of each side and adding it together. Here, we will solve for the front, side, and top, and then multiply it by 2 to account for the back, other side, and bottom.
Top/Bottom:
12*8=96
96*2=192
Sides:
12*6=72
72*2=144
Front/Back:
8*6=48
48*2=96
Now we should add the areas if each side together.
192+144+96=432.
Therefore, the surface area of this figure is 432 square millimeters.
(B) To solve for this, we can just multiply the surface area by 3 since each millimeter is $3. I will assume that it means per millimeter as the conversion from millimeters to feet is very odd.
432*3=1296
Therefore, it would cost $1296 to tile the prism.
(C) Volume is simple as the formula is just l*w*h.
8*12*6=576
Therefore, the volume of the prism is 576 cubed millimeters.