To build an office building, the actual investment is 20 million yuan, which is 20% less than the planned investment. How much is the planned investment?
建造一幢办公楼，实际投资2,000万元，比计划投资节约二成，则计划投资多少万元．
<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">2_000 / (4/5)</gadget>
<output>2_500</output>

<result>2_500</result>