Answer:
[tex]x=-3[/tex]
Step-by-step explanation:
[tex]3(4x + 1) - 4x + 3 = -18[/tex]
Subtract 3 from both sides:
[tex]3\left(4x+1\right)-4x+3-3=-18-3[/tex]
[tex]3\left(4x+1\right)-4x=-21[/tex]
Expand:
[tex]3\times4x+3\times 1-4x=-21[/tex]
[tex]12x+3-4x=-21[/tex]
[tex]8x+3=-21[/tex]
Subtract 3 from both sides:
[tex]8x+3-3=-21-3[/tex]
[tex]8x=-24[/tex]
Divide both sides by 8:
[tex]\frac{8x}{8}=\frac{-24}{8}[/tex]
[tex]x=-3[/tex]
