During the summer vacation, my mother enrolled me in a composition class. The first class was on July 15th and ended on August 7th. How many days did I take in total?
暑假里，妈妈给我报了作文班，第一次上课是7月15日，8月7日结束，问总共上了几天课？
<gadget id="calculator">31 - 15</gadget>
<output>16</output>

<gadget id="calculator">16 + 1</gadget>
<output>17</output>

<gadget id="calculator">17 + 7</gadget>
<output>24</output>

<result>24</result>