Xiaoying wants to type a 504-word article, and can type 42 words per minute on average. She has already typed for 7 minutes, how many more minutes will she have to type? (solution by equation)
小英要打一篇504字的文章，平均每分钟能打42字，已经打了7分钟，还要打多少分钟？(用方程解)
<gadget id="calculator">42 * 7</gadget>
<output>294</output>

<gadget id="calculator">504 - 294</gadget>
<output>210</output>

<gadget id="calculator">210 / 42</gadget>
<output>5</output>

<result>5</result>