Xiao Ming goes to the experimental school at 7 o'clock in the morning and goes home after school at 5 o'clock in the afternoon. How many hours does he spend at school?
小明早上7时到实验学校上课，下午5时放学回家，他在学校的时间是多少小时．
<gadget id="calculator">5 + 12</gadget>
<output>17</output>

<gadget id="calculator">17 - 7</gadget>
<output>10</output>

<result>10</result>