(12) In space, there are 9 points, among which no 4 points are coplanar. Connect several line segments between these 9 points so that there is no tetrahedron in the graph, then the maximum number of triangles in the graph is $\qquad$ .
(12) Divide 9 points into 3 groups, with no lines connecting any two points in the same group, and lines connecting any two points from different groups. For any 4 points, at least two points are in the same group, so there is no tetrahedron. Therefore, there are at most $\mathrm{C}_{3}^{1} \mathrm{C}_{3}^{1} \mathrm{C}_{3}^{1}=27$ (triangles).