Answer:
There are 25 students in the class.
Step-by-step explanation:
Since we know the percentage of students who want an ice cream party is 20%, and 5 students want an ice cream party, we know that:

, where S is the total amount of students. We can then solve for S:
Given equation
Multiply by S
Divide by 0.2
Therefore, there are 25 students in the class.