Resposta :
[tex]\sf x + 20 + 10x + x + 40 = 180[/tex]
[tex]\sf x + 10x + x = 180 - 40 - 20[/tex]
[tex]\sf 12x = 180 - 60[/tex]
[tex]\sf 12x = 120[/tex]
[tex]\sf x = \dfrac{120}{12} [/tex]
[tex]\red{\sf x = 10°}[/tex]
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[tex]\sf x + 20 + 10x + x + 40 = 180[/tex]
[tex]\sf x + 10x + x = 180 - 40 - 20[/tex]
[tex]\sf 12x = 180 - 60[/tex]
[tex]\sf 12x = 120[/tex]
[tex]\sf x = \dfrac{120}{12} [/tex]
[tex]\red{\sf x = 10°}[/tex]