How to calculate point y with given point x of a angled line I dropped out of school to early I guess, but I bet you guys can help me here.
I've got a sloped line starting from point a(0|130) and ending at b(700|0).
I need an equation to calculate the y-coordinate when the point x is given, e.g. 300. Can someone help me please ? 
Sorry for asking such a dumb question, can't find any answer here, propably just too silly to get the math slang ;)

You want the two point form of a linear equation.  If your points are $(x_1,y_1)$ and $(x_2,y_2)$, the equation is $y-y_1=(x-x_1)\frac{y_2-y_1}{x_2-x_1}$.  In your case, $y=-\frac{130}{700}(x-700)$
