Bill made a profit of 10% by selling a product. If he had purchased that product for 10% less and sold it at a profit of 30%, he would have received $42 more. What was his original selling price?  Choose the correct choice from the following:
A) $480
B) $570
C) $660
D) $720
E) $850
Let P be the original purchase price of the product.   Bill originally sold the product for 1.1*P.   In the second scenario, the purchase price is 0.9*P.   A 30% profit means the selling price would be 1.3*0.9*P = 1.17*P   Thus, according to the information in the question, 1.17P - 1.1P = 42   0.07 = 42   P = 600   The original selling price was  600*1.1= 
<gadget id="calculator"> 600*1.1</gadget>
<output>660</output>
660.   The correct answer is $660.
<result>C</result>
Bill made a profit of 10% by selling a product. If he had purchased that product for 10% less and sold it at a profit of 30%, he would have received $42 more. What was his original selling price?