I don't understand anything in the math book. The simplest thing is to read the knowledge points in each chapter and do the exercises in the book by yourself. Until it is finished. Then, do the basic and intermediate exercises at the back of the book. In this way, you will at least know all the knowledge.
Also, poor math means that you will lose a lot of points in basic problems and lose points in a kind of knowledge repeatedly. In this case, you need to study all the basic questions on the test paper, regardless of the questions behind the test paper. Try to do all the wrong questions on the basic test paper first, and then write down the knowledge points that are easy to make mistakes separately.
Mathematics is a subject that needs to be accumulated. What you have to do is to do more questions and learn the basics well first. At least you can pass the exam. What you need is to ask teachers and classmates directly when you can't. I believe they will be happy to help you.
Preparing for the exam requires a mentality. You need to adjust your mentality. Stick to it, because if you want good results, there is no other way but to work hard. If you can't persist, you can talk to your mother and show your efforts. In this way, you can also relieve your depression.
I believe that if you can persist, there will be good results. Later, in retrospect, I felt it was worthwhile and learned a lot.