Your statistics teacher announces a twenty-page reading assignment on Monday that is to be finished by Thursday morning. You intend to read the first x1 pages Monday, the next x2 pages Tuesday, and the final x3 pages Wednesday, where x1 + x2 + x3 = 20, and each xi ≥ 1. In how many ways can you complete the assignment? That is, how many different sets of values can be chosen for x1,x2, and x3?