The typist wants to type a 1200-word article, and has already typed some, and there are 280 characters left to type. How many words has he typed? (column equation solution)
打字员要打一篇1200字的文章，已经打了一些，还剩280字没打．他已经打了多少字？(列方程解答)
<gadget id="calculator">1_200 - 280</gadget>
<output>920</output>

<result>920</result>