The math books teaching the formulas for calculating interest is not the same as personal finance education. As a geek of course I knew all the formulas, I couldn't even take a math class my senior year because I took Calculus as a junior and they ran out of possible math classes for me to take. But although I knew all the formulas, nope, I can't recall any math problems, or any explanations/descriptions, relating to: how credit cards work, minimum payments, grace periods before interest starts, the fact that after paying interest you have to pay it off and wait a full period before the grace period resumes, how balance transfers work... and that's just credit cards, and just the basics, not the more advanced topics like travel points/cashback, signup bonuses, churning, etc which you probably shouldn't be teaching kids anyway.
Nor was I ever taught anything about savings accounts, tax-deferred retirement accounts, stock investing, etc. Although I hear stock investing in particular does come up in a lot of schools because it's "fun". But I never had any teachers let us play the stock market for fun, I totally would have been into that. I was never even shown a tax form in school, let alone had it explained.
I was able to do my own taxes because my dad showed me how. My mom showed me how to balance a checkbook, although that rapidly became useless knowledge when I could start monitoring my account online on a daily basis :) The rest I just kinda figured out, or didn't. My dad told me credit cards were bad but never explained them, ended up getting in debt, have been out of debt for a few years and now use credit cards responsibly -- "pay off in full to get the cashback, never pay interest". Nope nobody ever told me that either.