Is it done right here?

The formula of a slope:
[tex]m=\dfrac{y_2-y_1}{x_2-x_1}[/tex]
7. (5, 3), (10, 8)
[tex]m=\dfrac{8-3}{10-5}=\dfrac{5}{5}=1[/tex]
8. (-5, 14), (-1, 2)
[tex]m=\dfrac{2-14}{-1-(-5)}=\dfrac{-12}{4}=-3[/tex]
9. (-5, 6), (8, 6)
[tex]m=\dfrac{6-6}{8-(-5)}=\dfrac{0}{13}=0[/tex]
10. (-4, -17), (-4, -3)
[tex]m=\dfrac{-3-(-17)}{-4-(-4)}=\dfrac{14}{0}\ !!!![/tex]
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11. (12, -7), (2, -2)
[tex]m=\dfrac{-2-(-7)}{2-12}=\dfrac{5}{-10}=-\dfrac{1}{2}=-0.5[/tex]
12. (-3, -10), (-1, -1)
[tex]m=\dfrac{-1-(-10)}{-1-(-3)}=\dfrac{9}{2}=4.5[/tex]