Final answer:
The number of students in Miss Song's math class is 5, as they can equally divide the given 15 pens and 40 pencils without any remainder.
Step-by-step explanation:
The question asks for the number of students in Miss Song's math class, given that she evenly distributes 15 pens and 40 pencils amongst the students. To solve this problem, we need to find a common factor between the number of pens and pencils. The largest common factor they share is 5, as 15 pens can be divided among 5 students (3 pens each) and 40 pencils can also be divided among 5 students (8 pencils each), with no pens or pencils left over. Therefore, there are 5 students in the math group.