Answer:
r = - 2
Step-by-step explanation:
Use the slope formula to find m then equate to - 1
m = [tex]\frac{y_{2}-y_{1} }{x_{2}-x_{1} }[/tex]
with (x₁, y₁ ) = (6, r) and (x₂, y₂ ) = (9, - 5)
m = [tex]\frac{-5-r}{9-6}[/tex] = [tex]\frac{-5-r}{3}[/tex] = - 1 ( multiply both sides by 3 )
- 5 - r = - 3 ( add 5 to both sides )
- r = 2 ( multiply both sides by - 1 )
r = - 2
