Given:
Let x student in six grade :
So 40% of "x" is.
[tex]=x\times\frac{40}{100}[/tex]40% of x is 100 then:
[tex]\begin{gathered} 100=x\times\frac{40}{100} \\ \frac{100\times100}{40}=x \\ 5\times50=x \\ x=250 \end{gathered}[/tex]So 250 student in six grade .