Final answer:
The ratio of counselors to girls is 1:3. For every counselor, there are three girls.
Step-by-step explanation:
To write the ratio of counselors to girls, we need to compare the number of counselors to the number of girls. There are 10 counselors and 30 girls. The ratio is 10:30, which can be simplified to 1:3.
The ratio of counselors to girls is 1:3. This means that for every counselor, there are three girls.