Question

In a school 4/5 of the children are boys and the number of girls is 100. What is the number of boys?

Answer 1

Boys are 4/5 of total children.
So girls are 1-4/5=1/5 of total children.
Let total children be x, then
x/5=100
→x=500

So total boys=500-100=400

Hope my ans was easy to get

Answer 2

Let the total number of students be x

x+ $\frac{4}{5}$x=100
5x-4x=5 x 100
x=500

Therefore number of boys= 400