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Explanation:
There are two methods you could use. The first method involves the remote interior angle theorem. This says the remote interior angles (the two y angles) add to the exterior angle (130)
y+y = 130
2y = 130
y = 130/2
y = 65
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Or we could find the interior angle that is adjacent to the 130 degree angle. This is 180-130 = 50 degrees. So this is the top interior angle of the triangle. For any triangle, the three interior angles always add to 180
angle1+angle2+angle3 = 180
y+y+50 = 180
2y+50 = 180
2y = 180-50
2y = 130 ... from here on out, the steps are the same as above
y = 130/2
y = 65
So this helps show how the remote interior angle theorem is set up