12. [tex] \frac{r-3}{-4-(-8)} = -5[/tex]
[tex] \frac{r-3}{4} = -5[/tex]
r - 3 = 4(-5)
r - 3 = -20
r = -20 + 3
r = -17
13. [tex] \frac{r-2}{-2-5} = \frac{5}{6} [/tex]
[tex] \frac{r-2}{-7} = \frac{5}{6} [/tex]
6(r - 2) = -7(5)
6r - 12 = -35
6r = -35 + 12
6r = - 23
r = [tex] \frac{-23}{6} [/tex]
