Answer :
Answer: QN = 12
Step-by-step explanation: This quadrilateral is a paralelogram because its 2 opposite sides (NP and MQ) are parallel and the other 2 (MN and PQ) are congruent.
In paralelogram, diagonals bisect each other, which means QR = RN.
If QR = RN:
QR = 6
Then,
QN = QR + RN
QN = 6 + 6
QN = 12
The diagonal QN of quadrilateral MNPQ is QN = 12.