You and your friend want to take graduation pictures with a few of your fellow computer science class- mates, making 10 of you in total. You hired a very expensive photographer for the occasion and want to make the most of the experience. You want to select four students to stand in the front of the group in a line. In how many ways is it possible to take the pictures such that... (a) you have a place at the front of the group photo? (b) you and your friend have a place together at the front of the group photo?