Answer:
[tex]\frac{3}{11}=\frac{21}{y}[/tex]
Step-by-step explanation:
3 boys -> 8 girls -> 11 students
21 boys -> _____ -> y students
This information is lined up for you to solve for your number of students, y:
Looking vertically you could say the proportion is:
[tex]\frac{3}{21}=\frac{11}{y}[/tex]
Looking horizontally you could say the proportion is:
[tex]\frac{3}{11}=\frac{21}{y}[/tex]
There are other ways to write this but this last one I wrote answers your question.
