To build a building, the actual investment is 8.4 million yuan, which is 5% more than the plan. How much is the planned investment?
建筑一座楼房，实际投资840万元，超过计划5%，计划投资多少万元？
<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 + (1/20)</gadget>
<output>21/20 = around 1.05</output>

<gadget id="calculator">840 / (21/20)</gadget>
<output>800</output>

<result>800</result>