Answer:
r = - 11
Step-by-step explanation:
Calculate the slope m using the slope formula and equate to - 4
m = [tex]\frac{y_{2}-y_{1} }{x_{2}-x_{1} }[/tex]
with (x₁, y₁ ) = (4, 5) and (x₂, y₂ ) = (8, r)
m = [tex]\frac{r-5}{8-4}[/tex] = [tex]\frac{r-5}{4}[/tex] = - 4 ( multiply both sides by 4 )
r - 5 = - 16 ( add 5 to both sides )
r = - 11
