Respuesta :

clarch19

Answer:

r = 6

Step-by-step explanation:

(12-r) / ((-3-(-1)) = -3/1

[tex]\frac{12-r}{-2}[/tex] = -3

cross-multiply:  

12 - r = 6

subtract 12 from each side:

-r = -6

divide each side by -1:

r = 6