Mr. Li ordered 80 pieces of clothes each priced at 100 yuan from the store. Mr. Li said to the store manager: "If you are willing to reduce the price, then minus 5% of the price, I will order 20 more pieces." The store manager forgets After a while, the profit obtained is 100 yuan more than the original one. What is the cost of this commodity?
李先生向商店订购了每件定价100元的衣服80件，李先生对商店经理说："如果你肯减价，那么减去定价的5%，我就多订20件"，商店经理算了一下，获得的利润反而比原来多100元，则这种商品的成本是多少？
<gadget id="calculator">100 * 80</gadget>
<output>8_000</output>

<gadget id="calculator">100 * 20</gadget>
<output>2_000</output>

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

<gadget id="calculator">100 * (1/20) * 80</gadget>
<output>400</output>

<gadget id="calculator">100 * (1/20) * 20</gadget>
<output>100</output>

<gadget id="calculator">2_000 - 8_000 - 100 - 400 - 100</gadget>
<output>-6_600</output>

<gadget id="calculator">8_000 + (-6_600)</gadget>
<output>1_400</output>

<gadget id="calculator">20 - 80</gadget>
<output>-60</output>

<gadget id="calculator">80 + (-60)</gadget>
<output>20</output>

<gadget id="calculator">1_400 / 20</gadget>
<output>70</output>

<result>70</result>