Resposta :
[tex]5x-12=8+x[/tex]
[tex]5x-x=8+12[/tex]
[tex]4x=20[/tex]
[tex]x=\frac{20}{4}[/tex]
[tex]x=5[/tex]
[tex]\large\begin{array}{l}\mathtt{5x-12=8+x}\\\mathtt{5x-x=8+12}\\\mathtt{4x=20}\\\mathtt{x=\dfrac{20}{4}}\\\\\boxed{\mathtt{\red{x=5}}}\end{array}[/tex]