Both these angles are vertically opposite angles due to which their angle measures will be equal .
Which means :-
[tex]12x + 9 =13 x + 1[/tex]
[tex]9 = 13x + 1 - 12x[/tex]
[tex]9 = 1x + 1[/tex]
[tex]1x + 1 = 9[/tex]
[tex]x + 1 = 9[/tex]
[tex]x = 9 - 1[/tex]
[tex]x = 8[/tex]
Which means :-
angle 12x + 9 =
= 12 × 8 + 9
= 96 + 9
= 105°
angle 13x + 1 =
= 13 × 8 + 1
= 104 + 1
= 105°
Therefore :-
angle 12x + 9 = 105° ( x = 8)
angle 13x + 1 = 105° ( x = 8 )
