We prove a conjecture of Erdos, Purdy, and Straus on the number of distinct areas of triangles determined by a set of n points in the plane. We show that if P is a set of n points in the plane, not all on one line, then P determines at least n-1 2 triangles with pairwise distinct areas. Moreover, one can find such n-1 2 triangles all sharing a common edge.