Xiaofang went to bed at 9:00 p.m. and got up at 6:00 a.m. the next morning. How many hours did she sleep?
小芳晚上9时睡觉，第二天早上6时起床，她睡了多少小时．
<gadget id="calculator">12 - 9</gadget>
<output>3</output>

<gadget id="calculator">3 + 6</gadget>
<output>9</output>

<result>9</result>