Answer:
30 students
Explanation:
you have a ratio, and an unknown amount, so set up a proportion
I used x because the amount of boys is unknown
so then, cross multiply
(so do 3 times x, and 2 times 18)
![3x=36](https://img.qammunity.org/2021/formulas/mathematics/middle-school/o2rlra92n822na7k07r76iknc5v09e6et6.png)
then divide both sides by 3 to get x by itself, and you get
![x=12](https://img.qammunity.org/2021/formulas/mathematics/middle-school/kzh72we7ptn8hlgavxhsl5e208kjtiramm.png)
this means there are 12 boys in the class. because the problem is asking for the total number of students, add 12 and 18 (the number of boys and girls).
you get 30, so there are 30 students in her class.