Question

$\frac{1}{5}{}^{th}$ of the total number of students in a class are boys. If there are 20 girls in the class, how many boys are there?

Answer 1

$\frac{1}{5}{}^{th}$ of the students are boys, which means, $\frac{4}{5}{}^{th}$ of the total number of students are girls.
$\frac{4}{5}{}^{th}$ of the total strength = 20.
So, $\frac{1}{5}{}^{th}$ of the total strength = 20 ÷ 4 = 5. So, there are 5 boys in the class.