Answer:
interior angle = 58°; exterior angle = 122°
Explanation:
For all polygons, an interior angle and its accompanying exterior angle are always supplementary and thus equal 180°.
Thus, we can first find g by making the sum of the equation given for the interior angle and the equation given for the exterior angle equal to 180 and solve for g:

Now, we can first find the measure of interior angle X by plugging in g for 21:

Finally, we can find the measure of the exterior angle by either plugging in g for the equation or simply by subtracting 58 from 180 since the interior and exterior angle are supplementary and equal 180:
Exterior angle = 180 - 58
Exterior angle = 122