Răspuns: [tex]\red{\bf x=21^{\circ}}[/tex]
Explicație pas cu pas:
✳ Suma masurilor unghiurilor unui patrulater complex este de 360°
[tex]\bf 31^{\circ} + 149^{\circ} + (7x+2)^{\circ} +(2x-11)^{\circ}=360^{\circ}[/tex]
[tex]\bf 180^{\circ} + 7x^{\circ}+2^{\circ} +2x^{\circ}-11^{\circ}=360^{\circ}[/tex]
[tex]\bf 171^{\circ} + 9x^{\circ}=360^{\circ}[/tex]
[tex]\bf 9x^{\circ}=360^{\circ}-171^{\circ}[/tex]
[tex]\bf 9x^{\circ}=189^{\circ} ~~~\bigg|:9[/tex]
[tex]\red{\boxed{\bf x=21^{\circ}}}[/tex]
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