Mr. Zhang has 66 compositions to correct, and 12 have already been corrected. If 9 articles are corrected every hour, how many hours will it take to complete the correction?
张老师要批改66篇作文，已经批改了12篇．如果每小时批改9篇，还需要多少小时才批改完？
<gadget id="calculator">66 - 12</gadget>
<output>54</output>

<gadget id="calculator">54 / 9</gadget>
<output>6</output>

<result>6</result>