Answer:
r = 3
Step-by-step explanation:
Calculate the slope using the slope formula
m = (y₂ - y₁ )/ (x₂ - x₁ )
with (x₁, y₁ ) = (- 1, - 3) and (x₂, y₂ ) = (7, r)
m = [tex]\frac{r+3}{7+1}[/tex] = [tex]\frac{r+3}{8}[/tex]
Equating the 2 slopes, that is
[tex]\frac{r+3}{8}[/tex] = [tex]\frac{3}{4}[/tex] ( cross- multiply )
4(r + 3) = 24 ( divide both sides by 4 )
r + 3 = 6 ( subtract 3 from both sides )
r = 3
