Answer:
A, B, E
Explanation:
A is true since the sum of the measures of two consecutive angles of a parallelogram is 180 deg.
B is true since opposite angles of a parallelogram are congruent.
C is false since that equation gives x = -1, but x cannot equal -1 since that would make angle 3x - 12 have a negative measure.
D is false for the same reason as choice C.
E is true since x = 20 is the solution of the equations in choices A and B.