If the equation of the line is linear function, then the solution consist of theese steps:
1. equation of line y=kx+b, where k and b - numbers, x and y coordinates of points.
2. using the equation of the line it is possible to substitute coordinates of points into equation:
[tex] \left \{ {{-7=-8*k+b} \atop {-9=0*k+b}} \right. \ =\ \textgreater \ \ \left \{ {{-8k+b=-7} \atop {b=-9}} \right. \ =\ \textgreater \ \ \left \{ {{k=- \frac{1}{4}} \atop {b=-9}} \right. [/tex]
3. the equation is:
[tex]y=- \frac{1}{4}x-9[/tex]
