System.Drawing.Drawing2D question

[PJ6]

I want to use GraphicsPath to represent several 2D functions over discreet
domains. Only, two questions I'm having trouble answering -

1. If I want to add one function to another, is there an efficient way to
add together their GraphicsPaths to form a new one?
2. How do I calculate the Y value on a GraphicsPath at any given X?

Paul