A merchant marks goods up by 75% and then offers a discount on the marked price. The profit that the merchant makes after offering the discount is 22.5%. What % discount did the merchant offer? Choose the correct choice:
A) 20 %  B) 25 %  C) 30 %  D) 35 %  E) 40 %

Rationale: let p be the original price of the goods and let x be the rate after the markup . ( 1.75 p ) * x = 1.225 p x = 1.225 / 1.75 = 0.7 which is a discount of 30 % . the answer is c .
Answer: C