The students have summer vacation on July 10th, and come to school on September 1st. How many days are there in the summer vacation?
学生7月10日放暑假，9月1日到校上课，暑假共多少天．
<gadget id="calculator">31 - 10</gadget>
<output>21</output>

<gadget id="calculator">21 + 1 + 31</gadget>
<output>53</output>

<result>53</result>