How can I deal with my horrible maths teacher?

You are competent in Maths in a cl with incompetent teacher . I am afraid you could loose your abilities in Maths in such school environment. Could you change to another cl if other teacher is there ? Or could you change your school ,I know that it is very difficult decision to take. I was the first in my cl in Maths , but fortunately my teachers were liking the clever students in Maths . It is amazing to see that a clever student in maths be with conflict with a teacher that should be changed by school administration.