Answer: In the math club, there is one nine-year old, one eleven-year old, two twelve-year old, and 4 thirteen year olds.
Explanation:
Every dot represents one person in each category. So in order to figure out the math club, you count the dots. For example, in the 12 column. There are 2 dots meaning there are 2 people who are twelve years old in the math club. Hope this helped!