Yes there are definitely courses that would help with the kind of thing you're talking about. Probably the most accessible would be Khan Academy. That will expl

Yes there are definitely courses that would help with the kind of thing you're talking about. Probably the most accessible would be Khan Academy. That will explain all the "whys" of foundational stuff. Another approach that I recommend to people all the time is the Open University. Enrolling in a course is obviously a pretty big deal because they're expensive, but you can usually find used copies of the books on eBay etc. I'd recommend MST124 for the kind of stuff you're talking about. They're hands down the best, most comprehensive maths books I've ever seen. They're written for pure self-study, so you'll rarely have questions that aren't answered by the text or by the solutions to the exercises.