There is a pile of coal in the power plant, which has been used up (3/5), leaving exactly 7500 tons. How many tons was this pile of coal originally?
发电厂有一堆煤，用去了(3/5)，正好还剩7500吨．这堆煤原来有多少吨？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">7_500 / (2/5)</gadget>
<output>18_750</output>

<result>18_750</result>