Honghong went to bed at 9:00 p.m. and got up at 7:00 a.m. the next day. How many hours did she sleep in total?
红红晚上9时睡觉，第二天早上7时起床，她一共睡了多少小时．
<gadget id="calculator">3 + 7</gadget>
<output>10</output>

<result>10</result>