standard_description: Prove theorems about parallelograms. Theorems include: opposite sides are congruent, opposite angles are congruent, the diagonals of a parallelogram bisect each other, and conversely, rectangles are parallelograms with congruent diagonals.
problem_activity: Are the following two expressions equivalent? Explain your reasoning using the properties of operations. Provide examples to support your reasoning.
Expression 1:
$${(x-y)-z }$$
Expression 2:
$${x-(y-z)}$$


aligns: no