Xiaoli arrives at school at 7:00 am and ends at 11:00 am; arrives at school at 12:00 noon and ends at 5:00 pm. How many hours does Xiaoli spend at school that day?
小丽早上7：00到校，上午11：00放学；中午12：00到校，下午5：00放学．小丽这一天在校一共有多少小时．
<gadget id="calculator">11 - 7</gadget>
<output>4</output>

<gadget id="calculator">17 - 12</gadget>
<output>5</output>

<gadget id="calculator">4 + 5</gadget>
<output>9</output>

<result>9</result>