I'm guessing 8? But I'm not 100% positive
The answer is 100°
A parallelogram is any four sided shape with two pairs of opposite parallel and equal length sides. It is safe to say that a square is a parallelogram and not the other way round.
To explain how we got to 100 degrees, I have attached an image.
Based on the image attached, the opposite angles are equal. The adjacent angles are supplementary. With this in mind, the supplement of 80° will be 100°
It really is hard to say because there are many slots and we do not know what your teacher is teaching. I have seen a lot of teachers teaching out of date material. With that said, here is a list from best to worst.
PCI Express x16
PCI Express x1
AGP
PCI
This is list is based on greatest to least and base on the bandwidth read and write speed.