Li Jun has already typed 600 words for a manuscript, and the finished one is 20% more than the rest. How many words are left in this manuscript?
李军打一份稿件，已经打了600个字，已经完成了的比剩下的多20%，这份稿件还剩下多少个字？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">600 / (6/5)</gadget>
<output>500</output>

<result>500</result>