Respuesta :

fangqitu
6n=30+3n-12
6n-3n=30-12
3n=18
n=6
6n=30+3(n-4)
multiply 3 by n and 3 by -4
6n= 30+ (3n-(3*4))
6n=30+3n-12
subtract 3n from both sides. 
6n=30+3n-12
-3n       -3n
3n= 30-12
3n= 18 
and then you divide by 3
n= 6

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