Two issues. A kid who needs to learn algebra and a teacher who is less than effective. Fighting with the administration over the teacher's effectiveness might get a better grade for the kid in the long run but he probably won't really learn much. I'd pull him from the class and in writing explain my reasons for doing so to the administration, copying to the superintendent.
If he needs to stay in the class due to credit requirements or scheduling issues, seek out other forms of tutoring. There are online resources and courses. I would suggest that your emotional involvement with the issue; being pissed off at the teacher, will not make you a very effective tutor from this point on.
One lesson that I think it's important for kids to learn, especially if they are headed to college, is that there are always going to be good teachers and lousy ones and sometimes you just have to gut through on your own. Last year my son was in calculus as a college freshman. The instructor was a graduate assistant who spent most of his time flirting with the female students, presented all the lectures as power points and didn't offer any help or support. My kid needed the class to stay on his bio major track. He'd faced this before with an honors chemistry teacher in high school and knew it was up to him to find the help he needed. He did.
Good luck.

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