Resposta:
[tex]6x+20=40+2n\\\\\mathrm{Subtrair\:}20\mathrm{\:de\:ambos\:os\:lados}\\\\6x+20-20=40+2n-20\\\\\mathrm{Simplificar}\\\\6x=2n+20\\\\\mathrm{Dividir\:ambos\:os\:lados\:por\:}6\\\\\frac{6x}{6}=\frac{2n}{6}+\frac{20}{6}\\\\\mathrm{Dividir:}\:\frac{6}{6}=1\\\\=x\\\\\frac{2n}{6}+\frac{20}{6}\\\\\mathrm{Aplicar\:a\:regra}\:\frac{a}{c}\pm \frac{b}{c}=\frac{a\pm \:b}{c}\\\\\frac{2n+20}{6}\\\\\mathrm{Reescrever\:como}\\\\2n+2\cdot \:10\\\\2\left(n+10\right)\\\\\frac{2\left(n+10\right)}{6}[/tex]
[tex]\mathrm{Eliminar\:o\:fator\:comum:}\:2\\\\\frac{n+10}{3}\\\\x=\frac{n+10}{3}[/tex]
