The slope-point formula of a line:
[tex]y-y_1=m(x-x_1)[/tex]
We have:
[tex]m=2,\ (-8,\ 1)\to x_1=-8,\ y_1=1[/tex]
Substitute:
[tex]y-1=2(x-(-8))\\\\\boxed{y-1=2(x+8)}[/tex]
