Ahh, there’s the rub. Math is a practical skill, it’s not about memorizing someone else’s work. My first algebra teacher when I went back to school said if you want to do well in this class there’s 3 things you have to do, practice, practice, and…wait for it, practice. Ahh, good times.
No-one- and I’m not exaggerating or using hyperbole here, I really mean no-one- that I know IRL uses Algebra (in it’s “complicated technical-looking equations” format) for anything. So no, it’s not just “Since I don’t understand it, neither does anyone else”, since clearly lots of people do. They just all happen to be on the SDMB, which is why “Actually using algebraic equations in non-specialist tasks” is the latest addition to my “Stuff you only see on the SDMB and not in the real world” list.
I hear graph theory can be used to model a reasonable bit of music theory (i.e. chord progression, tonal quality, non-chord tones). Graph Theory certainly involves algebra (at least in a formal, proof-writing context). But I’m not certain about this, I heard it from a group at my school who are making a music game.