Answer: 60 girls
If the ratio of girls to boys is 5 to 6, it can be written as 5/6. You can use cross multiplication to figure out how many girls there are if there are 72 boys by setting the number of girls equal to x and dividing it by 72 like so:

After multiplying 5 and 72, and 6 and x, you get the equation

. To find the number of girls, all you have to do is divide by 6, which leaves you with

, meaning there are 60 girls when there are 72 boys based on the ratio 5:6 (girls to boys).