batch of commodities, if sold at the price, can make a profit of 10,000 yuan; if sold at 80% of the price, it can make a profit of 2,000 yuan. Excuse me: How much is the cost of this batch of goods?
一批商品，如果按定价出售，可得利润10000元；如果按定价的80%出售，还能盈利2000元．请问：这批商品的成本是多少元？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">10_000 * (4/5)</gadget>
<output>8_000</output>

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

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">6_000 / (1/5)</gadget>
<output>30_000</output>

<result>30_000</result>