Respuesta :

3x + x - 13 + 4 - 6x = 12
-2x - 9 = 12
-2x = 12 + 9
-2x = 21
x = 21/-2
x = -10.5


3x + x - 6x - 13 + 4 = 12 

-2x - 9 = 12 <-- add 9 both sides.. 

-2x - 9 + 9 = 12 + 9 

-2x = 21 <-- divide both sides by -2 

-2x/-2 = 21/-2 

x = -21/2 

The solution is -21/2 (or -10.5 or -10 1/2)