(a) [tex]\frac{6-8}{-4-4}=\frac{-2}{-8}=\boxed{1/4}[/tex]
(b) Using the point (4,8), we get [tex]\boxed{y-8=\frac{1}{4}(x-4)}[/tex]
(c) Rearranging into slope-intercept form,
[tex]y-8=\frac{1}{4}(x-4)\\\\y-8=\frac{1}{4}x-1\\\\\boxed{y=\frac{1}{4}x+7}[/tex]