C# Programm Gauß-Jordan algorithm

Hey. I am 16 and have been learning C# in School for 5 months now. Here is my program to solve a three-line Gauss-Jordan algorithm. It is far from finished so I was hoping for help here

Here you can edit the Code in realtime: codeshare.io/alAr3m
Here you can see the Code: goo.gl/NeYYhX
Music: youtu.be/je9bnuIqVVc