two-fifth of the students in a mixed school are boys. if there are 30 girls in the school how many are boys.

60

To find the number of boys in the school, we need to determine the total number of students in the school. Since we know that two-fifths (2/5) of the students are boys, this means that the remaining three-fifths (3/5) must be girls.

Given that there are 30 girls in the school, we can set up a proportion to find the total number of students:

(3/5) = 30/x

To solve for x, we can cross-multiply:

3*x = 5*30
3*x = 150

Now, divide both sides of the equation by 3:

x = 150/3
x = 50

Therefore, the total number of students in the school is 50. Now, to find the number of boys, we can calculate two-fifths of 50:

(2/5) * 50 = 20

Thus, there are 20 boys in the school.