I transferred schools in the middle of 10th grade, and the new Algebra class I landed in was several chapters ahead. I never caught up, but the teacher passed anyone who turned in literally anything for homework so I did that.
Now in my 30's I'm getting into indie game design, and I need that gap filled so I can write the code I need. So I went to the local thrift shop and picked up a couple old textbooks (since it's safe to assume that nothing groundbreaking has happened in the field of basic algebra in the past twenty years) for fifty cents and I've been working my way through them. I don't understand everything that's happening, but I'm pushing ahead with the faith that somewhere along the line things will "click".