There is a pile of coal in a certain factory, use up (1/4) of it in the first month, and use up the rest (1/5) in the second month. At this time, there are still 120 tons left. How many tons are there in this pile of coal?
某工厂有一堆煤，第一个月用去它的(1/4)，第二个月用去余下的(1/5)，这时还剩下120吨，这堆煤一共有多少吨？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">120 / (4/5) / (3/4)</gadget>
<output>200</output>

<result>200</result>