Answer: r = 1
Step-by-step explanation:
The slope of a line can be represented as [tex]\frac{y_2-y_1}{x_2-x_1}[/tex]. Plugging in the following values would provide you with:
[tex]\frac{(r)-(-5)}{(5)-(2)} =2[/tex]
[tex]\frac{r + 5}{3} = 2[/tex]
[tex]r + 5 = 6[/tex]
[tex]r = 1[/tex]
Hope it helps :) and let me know if you want me to elaborate on anything.