20% of a pile of sand is used up, and there are 1120 tons left. How many tons is this pile of sand?
一堆沙子用去20%，还剩下1120吨，这堆沙子有多少吨？
<gadget id="calculator">20 / 100</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_120 / (4/5)</gadget>
<output>1_400</output>

<result>1_400</result>