Respuesta :

-3n+9 = 3n + 9
9 = 0n + 9
n = 0

Answer

n= 0

Explanation

- 3 (n - 3) = 3n + 9−3(−3)=3+9

−3+9=3+9

−3=3

-3n=3n−3n=3n

−3−3=3−3

−6=0