In the regular nonagon shown, what is the measure of angle x? 36° 40° 45° 60°

The picture in the attached figure

we know that
the sum of the interior angles of a polygon is (n-2)*180
where
n is the number of sides.
For n=9 sides (a nonagon has nine sides)
the sum of the interior angles =(9-2)*180--------> 1260°

Is a regular nonagon
so
each interior angle has the same degrees:
1260/9=140 degrees

x is the exterior angle
exterior angle=180-interior angle-------> 180-140=40°

the answer is
the angle x measure 40°

Aand b is what i think