2. Students sit in the classroom in pairs. There are more girls in the class, so four fifths of the total number of students sit in mixed pairs (boy + girl), and there are three pairs that are exclusively female. How many boys, and how many girls are there in this class?
First method: In mixed pairs, $\frac{4}{5}$ of the class sits, so in female pairs, $\frac{1}{5}$ of the class sits.

$\mathrm{Here} \frac{1}{5}$ of the class consists of 6 girls sitting together,

1 POINT

which means there are $5 \cdot 6=30$ students in the class.

1 POINT

Of these 30 students, 24 students sit in mixed pairs, so there are 12 boys.

There are then 18 girls.