A radio manufacturer produces x sets per week at a total cost of $₹\begin{Bmatrix} \frac{x^2}{25}+3x+100\end{Bmatrix}$. He is a monopolist and the demand of his product is $x=75-3p $, where p is the price in rupees per se t. For maximum net revenue the number of sets produced per week is :

30 40 20 15

30