A side of the triangle below has been extended to form an exterior angle of 133º. Find the value of x. 133° 21° xo

In order to find the value of x, we need to remember that the sum of the interior angles of a triangle is 180°
so we have the next equation
21+x+(180-133)=180
21+x+47=180
x=180-21-47
x=112°