about mathematic

I sure that everyone learns mathematics when they in preschool, primary school, secondary school  even though in college or university.We learn a lot of different kinds of math such as algebra, circles,find x and y and etc.

I curious that why we should learn all that math which are very complex? do it apply in our life? in life we only use + - x / .We use all that to count money and etc.So, why we should learn all that complex math during school time? We should learn how to use + - x  more to count money. For  those who very good in math, of course they can get a A in their exam but for those who not good in this kind of complex math sure that they will get fail or just a pass rate.

But the things is we learn all that for what? just for knowledge? or something else? I truly 100% confirm that we won't use those math such as x and y or algebra to count money.For my opinion, I　think that is not necessary to learn all that complex math.