The rule of the slope of the line is
[tex]m=\frac{y2-y1}{x2-x1}[/tex](x1, y1) and (x2, y2) are two points on the line
Since the line passes through points (-1, 8) and (12, -5), then
x1 = -1 and y1 = 8
x2 = 12 and y2 = -5
Substitute theses values in the rule above to find m
[tex]m=\frac{-5-8}{12--1}=\frac{-13}{12+1}=\frac{-13}{13}=-1[/tex]The slope of the line is -1
