Answer
$60^{\circ};40^{\circ};80^{\circ}$
Work Step by Step
1. The exterior angle is equal to the sum of the two other angles
12x+40=12x+8x
20x-12x=40
8x=40
x=5
2. Plug x in to find the angles:
12(5)=60
8(5)=40
3rd angle: 180-40-60=80
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