Consecutive angles of a parallelogram are supplementary, so:

This means
and that
.
Since opposite angles of a parallelogram are congruent,

Answer:
120°
Step-by-step explanation:
sum of the measures of the interior angles of a hexagon

Answer: c. Level of Significance
This is the alpha value
alpha is a greek letter with the symbol 
A type 1 error is when the researcher rejects the null, but the null was true (meaning the researcher shouldn't have rejected the null).