QN = 142°
A semicircle will always be equal to 180°, and we have two measures for semicircle QO.
[tex]QO = 180\\MN = 90\\NO = 38\\\\QM = QO - MN - NO\\QM = 180 - 90 - 38\\QM = 52\\\\QN = QM + MN\\QN = 52 + 90\\QN = 142\\[/tex]
