If a class has 20 students and 12 are girls, what fraction of the class are boys?

To determine the fraction of the class that are boys, start by finding the number of boys in the class. Given that there are 20 students in total and 12 of them are girls, you can calculate the number of boys by subtracting the number of girls from the total number of students:

20 students - 12 girls = 8 boys.

Now that you have the count of boys, you can express this as a fraction of the total number of students. The fraction is given by the number of boys over the total number of students:

8 boys / 20 students.

To simplify this fraction, divide both the numerator and the denominator by their greatest common divisor, which is 4:

(8 ÷ 4) / (20 ÷ 4) = 2/5.

This shows that 2/5 of the class consists of boys. Therefore, this fraction correctly represents the proportion of boys in the class.