While selling to the retailer, a company allows 30% discount on the marked price of their products. If the retailer sells those products at marked price, his profit % will be = ?

Answer: Option D

Let the marked price = 100 units
According to the question,
$$\text{100(MP)}\stackrel{30\%\text{ discount}}{\to }\text{70(SP)}$$      $$\to$$ CP of retailer
Cost price of retailer = 70
Retailer sold at Marked price = 100
Profit = Marked price - Cost price
= 100 - 70
= 30 units profit
$$\begin{array}{rl}& \therefore \text{Profit }\%=\frac{30}{70}\times 100\\ & =42\frac{6}{7}\%\end{array}$$