Resposta:

x=13

Explicação passo a passo:

x-4=9

x=9+4

x=13

[tex]\Large\displaystyle\text{$\begin{gathered} \sf{x-4=9 } \end{gathered}$}[/tex]

[tex]\Large\displaystyle\text{$\begin{gathered} \sf{ x=9+4} \end{gathered}$}[/tex]

[tex]\Large\displaystyle\text{$\begin{gathered} \boxed{\boxed{\sf{ x=13}}} \end{gathered}$}[/tex]