Respuesta :

Apply angle sum property

[tex]\\ \tt\Rrightarrow 4x-12+63+45=180[/tex]

[tex]\\ \tt\Rrightarrow 4x+51+45=180[/tex]

[tex]\\ \tt\Rrightarrow 4x+96=180[/tex]

[tex]\\ \tt\Rrightarrow 4x=84[/tex]

[tex]\\ \tt\Rrightarrow x=21[/tex]

Answer:

x = 21°

Explanation:

All the interior angles of the triangle sum up to 180°

45 + 63 + 4x -12 = 180°

96° + 4x = 180°

4x = 180° - 96°

4x = 84°

x = 21°

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