Is it normal that i cry for no reason?

There's a reason, you may just not know what it is yet/how to interpret it

I was terrible at maths but I only really need it for sorting out bills and petrol make sure I dont over spend and for wieghing and measureing things at work giving my kids there calpol. Its normal to be bad at maths my partner is good at math so it even us out. depending on what career choice you choose maths can be important or not that but its always good to know

I cried at the end of Music & Lyrics.

Crying is a perfectly normal way to release stress.

Crying is just a release. It doesn't always have to do with sadness or anything specific. I dunno about how to get it to stop. Try getting angry instead? That's what I do, and punching things is pretty easy.