A shopkeeper sells his goods at cost price but uses a faulty meter that weighs 800 grams. Find the profit percent.
Choose the correct choice from the following answers.
A) 20  B) 15  C) 25  D) 18  E) 19

Rationale: "explanation : ( 100 + g ) / ( 100 + x ) = true measure / faulty measure x = 0 true measure = 1000 faulty measure = 800 100 + g / 100 + 0 = 1000 / 800 100 + g = 5 / 4 * 100 g = 25 answer : c"
Answer: C