We are supposed to solve the equation
[tex]6(2x-1)-12=3(7x+4)[/tex]Here, we need to apply the distributive laws on both sides.
Comment: The distributive laws say that
[tex]a(b+c)=ab+ac\text{ and }(b+c)a=ba+ca[/tex]Using this comment we get
[tex]6(2x-1)=6(2x)+6(-1)=12x-6[/tex][tex]3(7x+4)=3(7x)+3(4)=21x+12[/tex]Then, our equation becomes
[tex](12x-6)-12=21x+12[/tex][tex]12x-18=21x+12[/tex]Now, let's apply the rule: terms with x on the right-hand side, and the rest on the left-hand side, to obtain
[tex]-18-12=21x-12x[/tex][tex]-30=9x[/tex][tex]x=\frac{-30}{9}=-\frac{10}{3}[/tex]