We have to use the formula of the slope
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]Where,
[tex]x_1=2m,x_2=m-3,y_1=4,y_2=6,m=-5[/tex]Replacing all these values, we have
[tex]-5=\frac{6-4}{m-3-2m}[/tex]Now, we solve for m
[tex]\begin{gathered} -5=\frac{2}{-m-3} \\ -m-3=\frac{2}{-5} \\ -m=-\frac{2}{5}+3 \\ m=\frac{2}{5}-3=\frac{2-15}{5}=\frac{-13}{5} \end{gathered}[/tex]