A commodity is priced at a profit margin of 25%, and later on promotional activities, the price after a 20% discount is 64 yuan. How much does this item cost?
一种商品按25%的利润率定价，后来搞促销活动，打八折后的价格为64元．该商品的成本是多少？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(5/4) * (4/5)</gadget>
<output>1</output>

<gadget id="calculator">64 / 1</gadget>
<output>64</output>

<result>64</result>