People study one type of graphs called random graphs. (Random graphs were introduced by Paul Erdos, a famous mathematician.) Random graphs can be generated in the following way: Consider a set of n vertices. Placing the links (i.e., edges) randomly between the vertices, where each vertex pair is connected with the same probability p. Such a random graph is represented by G and we say that G is created by a (n, p)-model. Calculate the expected number of edges in a random graph G with n vertices using the (n, p)-model.