For a pile of coal, the ratio of the number of tons removed on the first day to the number of remaining tons is 1:4, and (3/5) tons are removed on the second day, which is the remaining (3/5) tons that have not been removed , How many tons of this pile of coal are there?
一堆煤，第一天运走的吨数与剩下的吨数比是1：4，第二天接着运走(3/5)吨，这是还剩下(3/5)没有运走，这堆煤共有多少吨？
<gadget id="calculator">1 + 4</gadget>
<output>5</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (3/5) - (1/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(3/5) / (1/5)</gadget>
<output>3</output>

<result>3</result>