Answer:
a) DC = 16
c) m∠DCB = 120°
e) m∠ABC = 60°
Explanation:
Part a
The opposite sides of a parallelogram are equal in length. Therefore, DC is the same length as AB.
As AB = 16, then DC = 16.

Part c
The opposite angles of a parallelogram are equal in measure. Therefore, m∠DCB is equal to m∠DAB.
As m∠DAB = 120°, then m∠DCB = 120°.

Part e
Adjacent angles of a parallelogram sum to 180°. Therefore:
⇒ m∠ABC + m∠DAB = 180°
⇒ m∠ABC + 120° = 180°
⇒ m∠ABC + 120° - 120° = 180° - 120°
⇒ m∠ABC = 60°