Boys and Girls in the Class
In Ms. Matthews' classroom, there are 12 boys and 15 girls. In Mr. Lopez's classroom, there are 8 boys and 6 girls. In Ms. Waddell's classroom, there are 4 boys and 5 girls.
 Which two classrooms have the same boytogirl ratio?
 On one occasion Ms. Matthews' class joined Mr. Lopez's class. What was the resulting boytogirl ratio for the newly combined classes?
 On another occasion Ms. Waddell's class joined Mr. Lopez's class. What was the resulting boytogirl ratio for the newly combined classes?
 Are your answers to the two questions above equivalent? What does this tell you about adding ratios?

Extensions 
Ms. Louvin's class has a boytogirl ratio of 5 to 6. At the end of the 1st, 2nd, and 3rd quarters, the class gets larger by two boys and one girl. So, by the end of the year, Ms. Louvin has 6 extra boys and 3 extra girls in her class since the beginning of the year. If the class never has more boys than girls, then what is Ms. Louvin's largest possible class size at the beginning of the year?

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