Answer : Option D

Explanation :

$MF#%\begin{align}
&\text{Let x is the maximum marks of the examination}\\\\\\\\
&\text{Marks that Arun got = 30 % of x = }\dfrac{30x}{100}\\
&\text{Given that Arun failed by 10 marks}\\
&\Rightarrow \text{Minimum Pass Mark } = \dfrac{30x}{100} + 10\text{......(Equation 1)}\\\\\\\\
&\text{Marks that Sujith got = 40 % of x = }\dfrac{40x}{100}\\
&\text{Given that Sujith got 15 marks more than the passing marks}\\
&\Rightarrow \dfrac{40x}{100} = \text{Minimum Pass Mark } + 15\\
&\Rightarrow \text{Minimum Pass Mark } = \dfrac{40x}{100} - 15 \text{......(Equation 2)}\\\\\\
&\text{From equations 1 and 2, we have}\\
&\dfrac{30x}{100} + 10 = \dfrac{40x}{100} - 15\\
&\Rightarrow \dfrac{10x}{100} = 10 + 15 = 25\\
&\Rightarrow \dfrac{x}{10} = 25\\
&\Rightarrow x = 10 \times 25 =250\\
&\Rightarrow \text{Maximum marks of the examination = x = }250\\\\
&\text{Substituting the value of x in Equation 1, we have}\\
&\text{Minimum Pass Mark = }\dfrac{30x}{100} + 10 = \dfrac{30 \times 250}{100} + 10 = 75 + 10 = 85
\end{align} $MF#%