How do I get the relative path of a file?

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C#

WPF

filepath

I am trying to find a way to get a relative path for a text file in my Visual Studio, C#, WPF solution.

Right now i have something that works great on my computer, but if the application is run on another computer it breaks when the text file is needed, because the file path is different.

Here is my current code:

StreamWriter File = new StreamWriter("C:\\User Program Files\\anything you want\\team-4\\Maths Formula App\\ParabolaInfo.txt");

File.Write(___informationBox_.Text);
File.Close();

var text = File.ReadAllText("C:\\User Program Files\\anything you want\\team-4\\Maths Formula App\\ParabolaInfo.txt");
           
___informationBox_.Text = text;

so i need a way to get the file with a relative path that i can understand.

What I have tried:

I have searched the internet and other websites like this one, but none of the answers make any sense to me.

Thank you.