Resposta:  2

Explicação passo a passo:

6x-3=9

6x=9+3

6x=12

x=12/6

x=2

[tex]\Large\displaystyle\text{$\begin{gathered} \sf{6x-3=9 } \end{gathered}$}[/tex]

[tex]\Large\displaystyle\text{$\begin{gathered} \sf{6x=9+3 } \end{gathered}$}[/tex]

[tex]\Large\displaystyle\text{$\begin{gathered} \sf{ 6x=12} \end{gathered}$}[/tex]

[tex]\Large\displaystyle\text{$\begin{gathered} \sf{x=\frac{12}{6} } \end{gathered}$}[/tex]

[tex]\Large\displaystyle\text{$\begin{gathered} \boxed{\boxed{\sf{ x=2}}} \end{gathered}$}[/tex]