You can use the white triangle as the separator first, and then the number of black triangles in front of the nth white triangle is 2, 3, 4, 5, ... n+ 1, so1+65438 is placed after the first white triangle.

The tenth white triangle is preceded by11+10+9+8+7+6+5+4+3+2 = 65 public black triangles, so * * has 74 triangles.

For the last question, the previous white triangle and black triangle can be regarded as the same item, and each triangle is: 3, 4, 5, 6, ..., n+2.

3+4+5+6= 18. At this time, it just reaches the fourth item, and then the two black triangles in the back row are 20 triangles. Therefore, there are 2+3+4+5+2= 16 black triangles and 4 white triangles.

Twenty triangles are shown in the figure ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲