(its part b to question 9 ) If there are 15 students who don't wear glasses how many students are there in class?

25

Step-by-step explanation:

so lets write our ratios.

Students that wear glasses to the whole class:

2 : 5

Students that wear glasses to those that dont:

2 : 3

And now if there are 15 kids in the class that dont wear glasses, that means that we have to multiply the second ratio by 5 to get the amount of students that don't wear glasses to 15. So now the second ratio will be

10 : 15

10 being amount of kids with glasses, and 15 kids without glasses. Now we just have to add them to get the answer of 25.