Simplify the expression.

Answer:
-2r^3+4r^2+12r-4
Step-by-step explanation:
6r^3-2r^2+12r-4-8r^3+6r^2
(6r^3-8r^3)+(-2r^2+6r^2)+12r-4
simplify
-2r^3+4r^3+12r-4