1, because the vertices overlap and the extension lines that are opposite to each other are on the same line. That is to say, from that vertex, one is to the left.

Draw lots, one to the right.

2. In addition, one side is overlapped, that is to say, any line drawn with that vertex constitutes these two angles.

3. The ratio of two angles is 5: 4, that is to say, the angle of 180 is divided into 9 parts, each part is 20, so one angle is 100 and the other is 80, and the difference between the two angles is 20.