BTW, puzzle # 9 (or chapter 2 puzzle 4)
there is a logic behind it
if you look, there are 4 large triangles, each made up of 4 smaller triangles, and in the smaller triangles the symbols all have number values, the object of this puzzle was to make the 4 small triangles in each of the 4 large triangles equal 23. that is, each of the large triangles has to have a total value of 23