A middle school science teacher wants to conduct some experiments. There are 15 students in the class. The teacher selects the students randomly to work together in groups of five. a. In how many ways can the teacher combine five of the students for the first group if order is not important? (3 points)
b. After the first group of five is selected, in how many ways can the teacher combine five of the remaining students if order is not important? (3 points)