Teacher Li has already typed 1600 words in a thesis, which happens to be the full text (2/5), how many words are left?
黎老师打一篇论文已经打了1600字，正好是全文的(2/5)，还有多少字没有打？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1_600 / (2/5)</gadget>
<output>4_000</output>

<gadget id="calculator">4_000 - 1_600</gadget>
<output>2_400</output>

<result>2_400</result>