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 = ?

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