Mr. Zhang ordered a certain product from the store, and he ordered 30 pieces in total, each priced at 100 yuan. Mr. Zhang said to the store manager: "If you are willing to reduce the price of each product by 1 yuan, then I will order 3 more pieces." "The store manager did some calculations. If the price is reduced by 4%, Mr. Zhang can still get the same amount of total profit because he ordered more. How much is the cost of this product?
张先生向商店订购某项商品，共订购30件，每件定价100元，张先生对商店经理说："如果你肯减价，每件商品每减价1元，那么我就多订购3件．"商店经理算了一下，如果减价4%，由于张先生多订购，仍可获得原来一样多的总利润，求这种商品的成本是多少元？
<gadget id="calculator">4 * 42</gadget>
<output>168</output>

<gadget id="calculator">42 - 30</gadget>
<output>12</output>

<gadget id="calculator">168 / 12</gadget>
<output>14</output>

<gadget id="calculator">100 - 14</gadget>
<output>86</output>

<result>86</result>