Respuesta :

They are supplementary angle so that means that they add up to 180 so:
[tex]31x+1+12x+7=180 [/tex]
[tex]43x+8=180[/tex]
[tex]43x=172[/tex]
[tex]x=4[/tex]
Racche
Adjacent angles
x=4
So the angles are supplementary, so set them equal to 180

31x + 1 + 12x + 7 = 180
 Solve
43x + 8 = 180
43x = 172
x = 4