Am 75 and retired. I received degrees in Mathematics and Electrical Engineering and taught Mathematics at the College level for several years. To fill up time since the pandemic limited my travel, I undertook to review areas on interest to me via courses provided by "The Great Courses" (TGC) company, which is at about the right level for me, and also by rereading some main authors in the math-science area. Have recently finished TGC offerings in calculus/vector calculus, linear algebra, number theory and have started the TGC offering in Physics given by Professor Wolfson, which will cover Newtonian mechanics, electromagnetism, thermodynamics, and modern physics. I have Professor Wolfson's "Explaining University Physics" texts - I see that I will need help on some of the more challenging problems, so I signed up. Cheers!