Two shopping malls, A and B, have the same price for product A. During the May 1st Golden Week, shopping mall A offers a 10% discount, while shopping mall B offers a 5% discount. After the golden week, on the basis of the promotional price, shopping mall A raises the price by 10%, and shopping mall B raises the price by 5%. As a result, there is a difference in the price of commodity A, and shopping mall A is 7.5 yuan lower than shopping mall B. Please explain why there is a price difference? What is the original price of this product.
甲乙两个商场对商品A的定价相同，五一黄金周期间，甲商场以九折促销，乙商场以九五折促销．黄金周过后，在促销价的基础上，甲商场提价10%，乙商场提价5%，结果对商品A的定价产生了差别，甲商场比乙商场低了7.5元．请解释为什么会产生差价？这种商品原定价是多少元．
<gadget id="calculator">95 / 100</gadget>
<output>19/20 = around 0.95</output>

<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 + (1/20)</gadget>
<output>21/20 = around 1.05</output>

<gadget id="calculator">(19/20) * (21/20)</gadget>
<output>399/400 = around 0.9975</output>

<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 + (1/10)</gadget>
<output>11/10 = around 1.1</output>

<gadget id="calculator">(9/10) * (11/10)</gadget>
<output>99/100 = around 0.99</output>

<gadget id="calculator">(399/400) - (99/100)</gadget>
<output>3/400 = around 0.0075</output>

<gadget id="calculator">7.5 / (3/400)</gadget>
<output>1_000</output>

<result>1_000</result>