if 20% is 6, then that means that 1/5 of the class is 6 students. in order to get to 100% (all of the students in class) we would need to multiply 6 x 5, since 6 is only 1/5 of the class, and we want to find the total number of the entire class. 6 x 5 = 30, meaning there are 30 students in the class altogether