[tex]A(x_1;\ y_1);\ B(x_2;\ y_2)\\The\ slope\ m=\dfrac{y_2-y_1}{x_2-x_1}\\\\(-2;\ k);\ (5;\ 3k-4);\ m=8.\\\\Subtitute:\\\\\dfrac{3k-4-k}{5-(-2)}=8\\\\\dfrac{2k-4}{7}=8\ \ \ \ \ |multiply\ both\ sides\ by\ 7\\\\2k-4=56\ \ \ \ |add\ 4\ to\ both\ sides\\\\2k=60\ \ \ \ \ |divide\ both\ sides\ by\ 2\\\\\boxed{k=30}[/tex]
