Answer:
If A=30 and B= 70 the first unknown angle Y would be 100. When using the E.A.T (exterior angle theorem) you add the 2 remote interior angles to get the exterior angle. (Y)
Unknown angle 2 is a interior angle, so we know all 3 of the interior angles must equal 180.
30+70=100
180-100=80
C=80
Explanation: