[tex]\tt Step-by-step~explanation:[/tex]
This equation is in slope-intercept form: y = mx + b, where m is the slope, and b is the y-intercept.
To find the slope of y = - 8 x - 3, we have to find what replaced m. -8 replaced m here, so -8 is the slope of this equation.
[tex]\Large\boxed{\tt Our~final~answer:~m=-8}[/tex]