[tex]\\ \bull\tt\longmapsto 2(31x+3)=192[/tex]
[tex]\\ \bull\tt\longmapsto 31x+3=\dfrac{192}{2}[/tex]
[tex]\\ \bull\tt\longmapsto 31x+3=96[/tex]
[tex]\\ \bull\tt\longmapsto 31x=96-3[/tex]
[tex]\\ \bull\tt\longmapsto 31x=93[/tex]
[tex]\\ \bull\tt\longmapsto x=\dfrac{93}{31}[/tex]
[tex]\\ \bull\tt\longmapsto x=3[/tex]
