First of all what fascist country fails 80% of students? Second, if its financially possible and doesn’t affect your GPA/transcript, I would recommend dropping some or all of your classes and retrying them next semester, after self-teaching those subjects so you are at an advantage instead of disadvantage. This is common in the US, but maybe the rules are different in your country. As for giving up, do you want to be a mathematician/physicist or not? If so, giving up is not an option. If not, why are you majoring in math in the first place?