We have to use the slope formula
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]Let's replace the points (9,-24) and (13,-21). Where
[tex]\begin{gathered} x_1=9 \\ x_2=13 \\ y_1=-24 \\ y_2=-21 \end{gathered}[/tex][tex]m=\frac{-21-(-24)}{13-9}=\frac{-21+24}{4}=\frac{3}{4}[/tex]