The slope of a line is;
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]Given the points;
[tex]\begin{gathered} (4,8),(2,12) \\ x_1=4,y_1=8,x_2=2,y_2=12 \end{gathered}[/tex]Then, the slope of the line that passes through the points is;
[tex]\begin{gathered} m=\frac{12-8}{2-4} \\ m=\frac{4}{-2} \\ m=-2 \end{gathered}[/tex]Hence, the slope m, is;
[tex]m=-2[/tex]