In a class, every student knows french or german (or both). 15 students know french, and 17 students know german. what is the largest possible number of students in that class? plz answer and show work?

32 students

Explanation:
We are given that:
Students in the class can either speak French, German or both
15 students know French
17 students know German

Now, the maximum number in the class can be calculated by assuming that no student can speak both languages.
This means that the number of students will be the summation of those who know French only (15) and those who know German only (17)

In this case:
the maximum number of students = 15 + 17 = 32 students 

Hope this helps :)