There are three chapters; The first chapter is triangle culvert, which mainly talks about how to solve triangle and several formulas of triangle. The second chapter is a series. Firstly, we should understand the concept of sequence, and secondly, we should understand the concepts of arithmetic progression and geometric progression. We must realize the use of arithmetic progression and geometric sequence in our life. The third chapter is widely used in our life, that is, the solution of inequalities and inequality groups. In this chapter, we should practice doing problems more and improve our practical ability.