Answer:
100°
Step-by-step explanation:
The bottom left and top left angle in a parallelogram are adjacent angles.
From the properties of parallelogram, we know adjacent angles are supplementary, this means they "add up to 180°"
<em>Thus, if one angle is 80, the other angles would be 100 (to make it total 180).</em>
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So, top left corner angle measures 100°