The logic follows here is:We know,93 = 729Therefore,It will have 9 × 9 cubes in a plane of cubes.So, The number of smaller cubes has exactly two painted faces = (n - 2) × 12? (9 - 2) × 12? 7 × 12? 84Hence, the correct answer is 84.Additional InformationIf a cube has been painted red, blue, and black on pairs of opposite faces and divide it into X parts.1) Total number of cubes = X32) Cubes that have three faces painted = 8 (Because there are only 8 corners in the cube)3) Cubes which has only two faces painted = (X - 2) × No of Edges (12)4) Cubes that have only one face painted = (X - 2)2 × 65) Cubes that have no face painted = (X - 2)3