In this question, it is given that there are 15 boys and 10 girls in Miss Li's class .
And she wants to group in such a way that each group have the same number of boys and girls .
We have to find, what is the greatest number of groups she can have, and for that, we have to find the greatest common factor(GCF) of 10 and 15 .
And the GCF of 10 and 15 is 5.
So she have 5 numbers of such groups .