Probability and conditional probability SAT question

The correct answer is $\frac{23}{60}$. It's given that one of the participants will be selected at random. The probability of selecting a participant from group A given that the participant is at least $10$ years of age is the number of participants in group A who are at least $10$ years of age divided by the total number of participants who are at least $10$ years of age. The table shows that in group A, there are $14$ participants who are $10$–$19$ years of age and $9$ participants who are $20+$ years of age. Therefore, there are $14+9$, or $23$, participants in group A who are at least $10$ years of age. The table also shows that there are a total of $30$ participants who are $10$–$19$ years of age and $30$ participants who are $20+$ years of age. Therefore, there are a total of $30+30$, or $60$, participants who are at least $10$ years of age. It follows that the probability of selecting a participant from group A given that the participant is at least $10$ years of age is $\frac{23}{60}$. Note that 23/60, .3833, and 0.383 are examples of ways to enter a correct answer.