Suppose you find seven articles related to the topic of your research paper. in how many ways can you choose five articles to read?

Assuming that the order in which the articles are chosen does not matter, the number of combinations of the seven articles taken five at a time is:

If the order in which the articles is chosen matters, then the number of permutations of 7 articles taken 5 at a time is:

Agc and bgd are vertical angles