batch of coal has already used 100 tons, accounting for (2/5) of this batch of coal and there are 20 tons more. How many tons of this batch of coal are there?
一批煤已用了100吨，占这批煤的(2/5)还多20吨，这批煤有多少吨？
<gadget id="calculator">100 - 20</gadget>
<output>80</output>

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

<gadget id="calculator">80 / (2/5)</gadget>
<output>200</output>

<result>200</result>