Answer:
Exterior angle = 20 degrees
Interior angle = 160 degrees
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Step-by-step explanation:
The phrasing "Each exterior angle measure is one eighth the measure of each interior angle" means,
exterior = (1/8)*(interior)
That rearranges to
interior = 8*(exterior)
Let's say x is the measure of the unknown exterior angle. That makes 8x the measure of the interior angle
The two must add to 180 to form a straight line.
interior + exterior = 180
8x + x = 180
9x = 180
x = 180/9
x = 20 is the measure of the exterior angle
8x = 8*20 = 160 is the measure of the interior angle
Note how 160+20 = 180 to verify our answers.