[tex]3x + 3 = 9[/tex]
[tex]3x = 9 - 3[/tex]
[tex]3x = 6[/tex]
[tex]x = 2[/tex]
_______________________
[tex] \frac{x}{4} - 2 = 1[/tex]
[tex] \frac{x}{4} = 1 + 2[/tex]
[tex] \frac{x}{4} = 3[/tex]
[tex]x = 3 \times 4 = 12[/tex]
_______________________
[tex]2(2x + 1) = x - 1[/tex]
[tex]4x + 2 = x - 1[/tex]
[tex]4x - x = - 1 - 2[/tex]
[tex]3x = - 3[/tex]
[tex]x = - 1[/tex]
