76. As shown in the figure, it is part of the pattern laid with tiles in a square, with a regular hexagonal tile at the center, surrounded by regular triangular and square tiles. The 1st layer from the inside out includes 6 square tiles and 6 regular triangular tiles, the 2nd layer includes 6 square tiles and 18 regular triangular tiles, and so on. The 8th layer contains how many regular triangular tiles.
answer: 90