Answer:
78°
Step-by-step explanation:
The two dashes on the triangle indicates that the two sides are equal in length. This means that the opposite angles of the two sides are equal, so there are two 51° angles.
[tex]51+51+x=180[/tex] (Angles of triangle sum to 180°)
[tex]102+x = 180[/tex]
[tex]x=78[/tex]
∴ [tex]x=78[/tex]°
Hope this helps :)
