A certain manufacturer increased its gross profit on a product from 10 percent of the cost of the product to 15 percent of the cost by changing the selling price. If the new selling price was $92.00 and the cost of the product remained the same, what was the old selling price?
Choose one.
A) $ 77.40  B) $ 80.00  C) $ 83.64  D) $ 87.40  E) $ 88.00

Rationale: given that { cost of the product } * 1.15 = $ 92 - - > { cost of the product } = $ 80 . the old price was $ 80 * 1.1 = $ 88 . answer : e .
Answer: E