I would go for Maths. It seems a more respectable subject than Business, and doing it will improve your mathematical skills, which from the looks of it are needed a lot more in uni, which is why they like Maths. However, if after a while you decide it's too hart, then drop it for the business (no point if you're going to get a really bad grade in it) so try it and see how it goes. But for me business seems like an irrelevant subject to what you are doing (I took business & economics and have since dropped them) whereas maths is completely relevant.