Respuesta :

12n * 2 = 24n
4n * 3 = 12n
(Simplifying the multiplication parts)

12n - 24n = -12n
-12n - 7n = -19n
(Simplifying the subtracting/Addition parts)

9 = 9
(You can't simplify the 9)

9 - 19n
(Putting it all together)

Hope This helps! :)