Xiao Ming goes to the experimental school at 8 o'clock in the morning and goes home after school at 4 o'clock in the afternoon. How many hours does he spend at school?
小明早上8时到实验学校上课，下午4时放学回家，他在学校的时间是多少小时．
<gadget id="calculator">4 + 12</gadget>
<output>16</output>

<gadget id="calculator">16 - 8</gadget>
<output>8</output>

<result>8</result>