Answer : Option A

Explanation :

Let the total number of students = x
Given that 20% of students are below 8 years of age
then The number of students above or equal to 8 years of age = 80% of x -----(Equation 1)
Given that number of students of 8 years of age = 48 -----(Equation 2)
Given that number of students above 8 years of age = 2/3 of number of students of 8 years of age

$MF#%\text{=> number of students above 8 years of age = }\dfrac{2}{3}\times48 = 32\text{-----(Equation 3)}
$MF#%

$MF#%\begin{align}
&\text{ 80% of x = 48 + 32 = 80}\\\\
&\Rightarrow \dfrac{80x}{100} = 80\\\\
&\Rightarrow \dfrac{x}{100} = 1\\\\
&\Rightarrow x = 100
\end{align} $MF#%