Answer:
I feel you bro I finally understood the question (i had the same one) just add the angle I will give an example after the answer
1 and 4
3 and 6
5 and 6 this one is right
2 and 8 and this one is right
two angles whose sum is 180°
one Obtuse Angle with an Acute Angle Will = 180°
and 180° is a straight line not too hard
Explanation: