Due to the influence of the "One Belt, One Road" national strategy, the import tariff of a certain commodity has been greatly reduced twice, the first time was reduced by 40%, and the second time was reduced by another 30% on the basis of the first reduction. How many dollars of tariffs should be charged on imported goods that are actually charged a tariff of US$5,040 now before the tax is reduced?
由于受"一带一路"国家战略策略的影响，某种商品的进口关税两次大幅度下调，第一次降低了40%，第二次在第一次降低的基础上再降低30%．现在实际收取关税5040美元的这种进口商品，在没有降税前应收取多少美元的关税？
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (3/10)</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">5_040 / (7/10) / (3/5)</gadget>
<output>12_000</output>

<result>12_000</result>