Official Solution:A merchant offers a 30% discount on her list price but still manages to make a profit of 19% on her cost price. What was her original profit percentage on the cost price before the discount?A. 76%
B. 70%
C. 57%
D. 55%
E. 49%
Let the original list price be \(p\) and the cost price be \(c\).
After a 30% discount, the selling price is \(0.7p\). Since she makes a 19% profit on her cost price, this selling price is equal to \(1.19c\). From this, we get \(0.7p = 1.19c\). This simplifies to \(\frac{7}{10}*p = \frac{119}{100}*c\), leading us to \(p = 1.7c\). Therefore, the original profit percentage on the cost price before the discount was 70%.
Answer: B