The fromula of a slope:
[tex]m=\dfrac{y_2-y_1}{x_2-x_1}[/tex]
a) (-1, -8), (-7, -4)
substitute
[tex]m=\dfrac{-4-(-8)}{-7-(-1)}=\dfrac{-4+8}{-7+1}=\dfrac{4}{-6}=-\dfrac{2}{3}[/tex]
b) (2.1, 3.8), (3.1, 7.6)
substitute
[tex]m=\dfrac{7.6-3.8}{3.1-2.1}=\dfrac{3.8}{1}=3.8[/tex]
