A pile of coal took away (1/5) of the total number for the first time, and (2/5) of the total amount was shipped for the second time, leaving 30 tons. How many tons does this pile of coal have?
一堆煤第一次运走了总数的(1/5)，第二次运了总数的(2/5)，还剩下30吨，这堆煤共有多少吨？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

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

<gadget id="calculator">30 / (2/5)</gadget>
<output>75</output>

<result>75</result>