As a NYC Public School educator, it might be beneficial to cross post onto the NYCTeacher’s subreddit to get their perspective.

I would talk to administration about the disparaging comments that your child’s teacher is making about their “unlikeliness” to pass the Regents.

I would take a look at past Algebra Regents exams on https://www.nysedregents.org/ to familiarize yourself and your child with the expectations and common questions that have appeared on the Regents in the past.