2x3=6+1=7 era so ver qual multiplo dava o antecessor do 7

[tex]\Large\displaystyle\text{$\begin{gathered} \sf{ 2x+1=7} \end{gathered}$}[/tex]

[tex]\Large\displaystyle\text{$\begin{gathered} \sf{ 2x=7-1} \end{gathered}$}[/tex]

[tex]\Large\displaystyle\text{$\begin{gathered} \sf{2x=6 } \end{gathered}$}[/tex]

[tex]\Large\displaystyle\text{$\begin{gathered} \sf{ x=\frac{6}{2}} \end{gathered}$}[/tex]

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