To print a manuscript, if you type 1800 words per hour, you can finish typing in 12 hours. If you want to finish typing in 9 hours, how many words per hour should you type? (Solve with ratio)
打印一份稿件，若每小时打1800个字，12小时可以打完，若要在9小时打完，每小时要打多少个字？(用比例解)
<gadget id="calculator">1_800 * 12</gadget>
<output>21_600</output>

<gadget id="calculator">21_600 / 9</gadget>
<output>2_400</output>

<result>2_400</result>