a ratio is how many X there are per Y. for example, a fraction is a ratio: 10/5 = 2 because there are 2 fives in a ten. but usually a ratio is written as x:y.
so to find these ratios, first we need to find the number of girls. 30 students-16 boys = 14 girls.
the ratio of girls to boys is 14:16 because there are 14 girls to every 16 boys. we simplify this to 7:8.
the ratio of girls to all students is 14:30. we simplify this to 7:15.
the ratio of boys to girls is 16:14, which simplifies to 8:7.
the ratio of boys to all students is 16:30, which simplifies to 8:15.