Answer:
The greatest number that she can have is 5 groups
Explanation:
This question plays on words, but refers to a concept that is quite familiar, and that is the Highest Common Factor of the two groups. The answer to this question is the highest number that can divide both group numbers without remainder.
15 boys: 3 × 5
10 girls: 2 × 5
So, she would have 5 groups, each having 3 boys and 2 girls