Chapter 6: Cartesian coordinate system (6. 1 plane rectangular coordinate system, 6.2 coordinate simple application method)
Chapter 7: Related fields of triangle (7. 1 triangle; 7.2 A polygon with a triangle inner angle of 7.3, the interior of which is related to the mosaic of 7.4 subjects)
Chapter 8: Binary linear equations (8. 1 binary linear simple formula 8.2 elimination method to solve linear equations, 8.3 8.4 practical problems of two sets of solutions of ternary equations, such as binary simple formula)