okay, let's go!
1. for the boys, 3 soccer is 5 basketball (in a group of 8 students).
2. for the girls, 7 soccer is 1 basketball (in a group of 8 students)
3. the question mentions 90 boys like soccer, which means we increased the number of boys surveyed 30x, since 3 times 30 is 90. now, we need to increase the girl numbers by 30 as well, giving us 210 girls who like soccer for every 30 who like basketball.
