Respuesta :
Note that sum of triangle interior angles is 180. So,
[tex](12x+12)+15+(3x+18)=180[/tex]
[tex]15x+45=180[/tex]
[tex]15x=135[/tex]
[tex]x=9[/tex]
Since [tex]A=12x+12=12.9+12=120[/tex]
And [tex]C=3x+18=3.9+18=45[/tex]
[tex](12x+12)+15+(3x+18)=180[/tex]
[tex]15x+45=180[/tex]
[tex]15x=135[/tex]
[tex]x=9[/tex]
Since [tex]A=12x+12=12.9+12=120[/tex]
And [tex]C=3x+18=3.9+18=45[/tex]