40, 50, 76, 104.
If we look at these numbers as angles and take them in pairs considering quadrants, the smaller of the first pair is the complement of the larger: 40=90-50. These angles complete the first quadrant.
In the second pair we consider the second quadrant: 90-180. The smaller of this pair is the supplement of the larger: 76=180-104. These angles complete the second quadrant.