Respuestas

2014-02-20T02:17:14+01:00
7x+8x-9=20x+21
7x+8x=20x+21+9
7x+8x-20x=21+9
-5x=30
x=30/-5
x=_6
  • Usuario de Brainly
2014-02-20T02:50:45+01:00
7x +8x -9 = 20x +21
15x -9 =20x+21
-9 -21 = 20x -15x
-30= 5x
-30/5 = x
-6 = x