You can go to some tutor schools, but it's expensive. I also worked as a teacher there, and it took my parents 100 yuan for an hour and a half. In fact, you can go to school to post some small notes or send some enlightenment on the intranet, so about 30 hours is enough, mainly depending on the student's school and his level. Generally, it is about 30 (two books) and 50 (one book), and key universities will be higher. But I'm talking about high school courses, primary school courses and junior high school courses, and it doesn't need to exceed 20, no matter what school.